I can't find that discussion back, but at least stack overflow (the granddady of stack exchanges), I seem to recall community wikis were not an encouraged practice.
Is the astronomy SE against, neutral or pro community wikis?
I think the gist of the opposition against community wiki is that much of the same could be achieved by proposing edits to an existing good answer, but then all the reputations etc. which is an important part of the general workings of an exchange isn't really included anymore.