The question
Proofs that every mathematician should know?
has 142 upvotes (4 down) and was favorited 150 times. The revision history shows that the question was closed by a moderator but with no other close voters listed.
https://math.stackexchange.com/posts/178940/revisions
Why was this question closed? Unless there is more information not in the revision history it looks like one user over-ruled the expressed opinion of more than 100 others. I searched the meta and could not find discussion of this closing.