User blog comment:TheSonofCharlusPotter/Features/@comment-29289194-20180514121043

Talk pages are easier to manage and very preferable to allowing people to leave comments on each other's pages. Talk pages encourage serious editors to use an appropriate and productive means to communicate, while comments can be tough to provide maintenance for and become trivial. I think it would encourage people who only use the discussions part of the wiki, to begin taking up the "special wiki activity" page with their trivial comments, making it tough to even work through what has changed on articles.

Achievements can become unproductive as well. It encourages people to keep editing for rewards rather than because they want to write, and begin uploading unneeded and unrelated pictures and changing info etc. for the sake of doing it.