Seems like there are some different views here.
So it would be helpful to hear from the team on this: Do you expect it will work fine to use Discourse to set up a wiki site? The method being to allow users to set up “wiki pages”–in the form of users creating wiki-fied posts.
(The reason to try this approach instead of using a full-on wiki tool like mediawiki would be that discourse is easy to use in general, looks great, etc.)