Consider a question as follows
Is it true that only Hinduism has the feature F?
Suppose it is clear that Hinduism has a feature F. I want to know whether Hinduism is the only way/religion that has feature F.
Such questions needs knowledge on all other existing religions also. So it seems off-topic.
But it can be viewed as a question that is asking about uniqueness of Hinduism. In this view it seems to be an on-topic question.
In this context, can I ask such questions in our main site?
Some sample questions:
Q1) Do Hinduism has large number of gods?
Q2) Do Hinduism is the only religion talking about sati sahagaman?
Q3) Do Hinduism is the only religion has stotras on sun?
Q4) Do any other religion contain Dattatreya?