We had a plenty of discussion already here and the votes to this question and several examples show how this can be misused. To make the mood lighter, let's have a funny story (Sorry for a long answer).
There was a boy studying in a middle school. He was preparing for an elocution competition conducted by his school management. He learned thoroughly about Cow and reached his school. Finally the hour came and the competitions started. After some time, it was his turn. He talked about it clearly. As follows.
Cow is very useful animal and gives us milk. Milk is considered as the complete and nutritious food. Cow is a domestic and religious animal. It has a large body, four legs, one long tail, two horns, two ear, two eyes, one big nose, one big mouth and one head. It is found in almost every regions of the country. In India, it is ritual and custom to worship Cow. Cow’s milk is used in the pooja, abhisek and other holy purposes. Cow is called by everyone as “Gau Mata” to give her mother like status in the Hindu religion......
The teachers were impressed with this essay. Gave good marks. As a second topic, they asked about "Sky". This made the boy startled. He only prepared for Cow essay. He had no idea about Sky. He thought for a minute and started talking about Sky.
Sky is what we call a blue appearance above our head. It appears blue in colour. There are many clouds in the sky. Clouds take in water from oceans, rivers and give us rain. If there are heavy rains, there will be greenery. Trees and plants grow. These plants and grass are food for domestic animals like Goat, Buffalo, Cow etc., Cow is a very useful animal and gives us milk. Milk is considered as the complete and nutritious food. Cow is a domestic and religious animal. It has a large body, four legs, one long tail, two horns, two ear, two eyes, one big nose, one big mouth and one head. It is found in almost every regions of the country. In India, it is ritual and custom to worship Cow. Cow’s milk is used in the pooja, abhisek and other holy purposes.........
So, he continued with Cow essay. His teachers did not give marks for his second essay. Why? Because he was talking about another topic to bring relation between two different topics.
I believe why I said this story now. We are not in a different situation. We received many questions like having "According to Hindu scriptures,", "What to scriptures say about ", "According to Hinduism"... This line has been the entry pass to bypass the off-topic check. It is turning to a Boat programming meme. Boat programming means a question posted on Stack Overflow which asked what is needed to program on a boat. The reason why it was asked was having the word "Programmers" in the question. It was eventually deleted by Jeff Atwood. Here the word is Hindu scriptures and any question can be made on-topic for the site using them.
Some may ask for examples. I have plenty of them. There was a question about origin of Dravidian languages. To those who don't know, questions regarding Indian languages are off-topic for our site (Not only Indian, any language. No bias). So, I pointed out that such questions are off-topic. After a comment, the OP realized that and self deleted that question. After a month or two, the same user has posted the same question. No change in the topic. It asked the origin of Dravidian languages. But this time, there was modification... yes there is a "What do Hindu scriptures say about origin of Dravidian languages". Voila, that was upvoted. I voted to close it and repeated almost the same comment. The reply was "What do Hindu Scriptures say". That comment was upvoted heavily and the reviews were favorable. There were not enough close votes on the question. It was answered too. If we look at both of the questions, there is nothing different. The gist is the same. If there is no phrase 'Hindu scriptures say' in the first question but the question is same. We are a site about Hinduism. Answers posted here are obviously from Hinduism point of view only (That is why the tag hindus was blacklisted). So, even if there is no mention of "Hinduism" or "scriptures" in the question, the answers will be the same. I do not see any difference between two variations. That will be the same. It will be off-topic only.
There is another type of modifying a question. We know that dream questions and personal advice questions are off-topic for our site. There was a question posted about asking how to interpret dead relatives in a dream and had details of that specific dream. That was closed as off-topic (with a mod intervention. I tried to reopen after editing but it failed). That was fine. After an year or two, there was another question asking the same i.e., But there is a modification in the question. The OP added a paragraph where dreams are discussed in Hinduism and gave an introductory passage of importance of dreams in Hinduism. (OP has some knowledge of Hinduism and a high rep user) The question is not closed as off-topic. That is open (reviewers chose to leave it open. Mod intervened again). If we remove that passage and look at the topic, that is asking about dream interpretation only. There are some questions which were made on-topic in this way. Irony is The question is not changed but there was a passage explaining their role in Hinduism. I don't think that makes a difference. Let us see how. For example, I have a question about horse riding.
Horse riding is a skill and one of the 64 sciences. This was taught to people in ancient India. Lord Krishna and Balarama learnt these skills in 64 days. Horse riding played a major role in Mahabharata war. Horses also have an importance in Hinduism. Lord Surya turned to a horse and beget Ashvini devatas. Nakula was a master in taming horses.
So, my question is According to Hindu scriptures, how to master horse riding? How to tame horses? Is there a text explaining this (which was taught in the ancient times)?
tags : scripture animals
So, is this a question about Hinduism and on-topic for us? If we remove that paragraph, that is definitely off-topic. The gist is learning about horse taming which is not a religious question. So, this should make clear. Same question if asked without that passage, that would be closed immediately. But the above question will be opened. That would also give place to bias based on reputation. The question not given importance but the word like Hindu scriptures is given importance. People who are not well versed with those topics have more probability of getting closed. So, there will be a bias which is a dangerous situation to handle.
This trend of making blatantly off-topic questions into on-topic by adding "Hindu scriptures" is a dangerous. Unfortunately, this is mostly done by users with access to moderator tools (names not required). That would definitely add a bad name to the site's reputation. There can be many variations like this. There can be 'n' number of questions about non Hinduism topics added with scriptural reference. It has reached to a state where users started advising to add the line to stay away from review queues.

Shiv Bhagvan ki mahanta koi Khuda nahi janta. Nearly everyone knows this. Like if you agree.
I don't know if the user said without knowing the help center and scope. But see the upvotes question and comment got! this raises question on the guidance we are giving to new users. Need to take care.
These are types of statements on social media which say "Like and RT if you agree." That too written in Non-English. Such questions are clearly off-topic for Stack Exchange. I have even received comments that it will be a valid question if "What do Hindu scriptures say" is added. It supports my statement that closeable and off-topic questions (like personal advice, scientific speculation, hypothetical) are converted into on-topic by adding that statement.
So, the question arises, why is it off-topic to ask a matter which is present in Hinduism books?
This is a valid question. But there is a huge disadvantage if everything present in Hindu texts is allowed. Hindu texts and sages talk about a wide range of topics almost everything. There is a mention of gravity, speed of light, rainbows, music, pets, cooking, public speaking, language, pleasing women (!) and so on. In the Brahma purana, there are chapters dedicated to water cycle. In the Brahmanda Purana, birth of animals is discussed. In the Narada Purana, there are chapters discussing music, mathematics. There are varied texts on different topics. By using some lines and sentences, we can easily bring relation between Hinduism and any non religious topic. IN other words we can manipulate. If we encourage questions based on the mention in the texts, then there is nothing off-topic for our site. The off-topic section from the help center can just be deleted. It is because Hindu texts talk about each and everything. So, going by that logic, we should allow questions about music, dance, mathematics, physics, chemistry, Cooking and all. We will turn into a site which accepts almost everything. So, that would make us a site of everything. This would only increase questions per day but those are not good questions as it also defeats the purpose of Stack Exchange to have a different sites to deal with different topics. It doesn't take much time to fill the site's questions with non religious questions with scriptural references. That would decrease quality. We should not to forget to Focus on quality.
If someone wants to have food, they should go to a restaurant not a movie theatre. This movie theatre owner may sell rice which he has but it is not a right way to recommend movie theatre to get food. Same applies here too. Same was said by Mad Scientist in their answer to Users asking for scientific answers / reasons
So, the solution we have is to allow questions which asks for scriptural reference of some belief or a practice (we do that and many questions are present already) and not references of some Non religious topics like environment, physics, cooking, dice etc.,
If a question is posted about "Scriptural reference about ". This 'X topic' should be a religious topic and not a scientific or other. If a question is asking scriptural reference about , then the question itself is about that topic. If there is a better site which answers better, we can also migrate.