I have been a member of Mathematics.SE for ten years. Yet I still don't understand why it is that when certain policies are introduced, they are not enforced or enforced selectively.
For example: puzzles. When I joined in 2012 there were many puzzles being posted. This was considered okay. Then one day I posted my own puzzle, a variation on an old Martin Gardner puzzle that I had worked on for quite some time. I was then informed that there was a new policy: puzzles were no longer welcome on MSE; it would be better if I posted my puzzle on a specialized website. Okay. My puzzle was deleted.
To my surprise, since that date MSE has accepted many puzzles. You would think that these would be met by the same warning that I got, or by downvotes, ultimately leading to the closing or deletion of the question. But no, apparently this never happens.
What is going on here ? Why do the moderators decline to enforce the policies agreed upon ?