In this answer, Pandya, one of the moderators, says
Though we have a policy of deleting unsourced answers after 15 days if sources are not added, we hardly delete the answers. Many unsourced answers are living on the site with post notice.
According to me, this site is great compared to other similar ones only because we have this "back it up from scriptures" rule for the answers. Otherwise, anyone can write whatever they want in answers.
Now, if users realize that their answers, despite not having sources as is necessary, are never going to get deleted then that is an incentive for them to post more such answers. Why would the users be willing do the extra hard work of finding the necessary sources if they know that they can get away by posting unsourced answers every time? Also, what difference does it make whether a banner is being added to the answer or not as long as the answers are visible to every reader browsing this site? If an answer is regarded as unfit, judging by the standard of this site, then it has to be removed. The post notice/banner's purpose must not be anything other than informing the concerned users that after the deadline is over the answers are going to be deleted.
If unsourced answers are not getting deleted then the very purpose of having the "back it up from scriptures (or other allowed sources)" rule is getting defeated.
So, I want to know the reason why these answers are not getting deleted even though the policy says otherwise?