User blog comment:BertH/New Forums now available in Labs/@comment-188432-20121202033808/@comment-26686429-20121202101634

This situation (users can edit their posts after they've been replied to) is a problem with almost all forum systems, that's one of the reasons why a "quote" button is so useful. Most forum systems, however - don't allow users to remove their own posts, I'm guessing this was done to try and replicate a wiki-style system. Ordinary users have the ability to remove their own posts from a wiki page, that edit is logged and any user can add it back. I havn't tested the new forum system, but I'm assuming the same thing applys.