Wikis that allow users to create content but not edit/delete the content afterwards may discourage users from contributing. Users will be reluctant to publish anything if they're on a “one way street” and can't make changes after they have contributed.
Users will be discouraged to contribute, or may publish only the bare minimum information. Pages can take a long time to be added because users are reviewing heavily before adding to the wiki.
Set permissions to allow users to edit or delete their own posts.