If you really want better comments, some forums place new members on moderation.
That way you can see that the comments they are making, and decide to allow them or not.

If they are requests, they can easily be blocked.

I’ve been on several forums where that is the case. If the new member posts enough quality posts,
then they are put on unmoderated, and are allowed to post to the forums.

Another method, is to have a forum thread, or area, just for new people. Once they make enough
posts, or meet some other criteria, then they are allowed to post in the other forums.

In both cases, they can still read posts from any forum.