Tallima: It's a tricky problem
OneFiercePuppy: Your solution doesn't seem to address the problem, though. Account removal accomplishes nothing, and the majority of current scammer/downrep-flood problems aren't with accounts that are even six *weeks* old, much less six months. Even if you hate me *so much* all the time, we never interact if you a) don't post about it b) don't PM me about it and c) don't downrep-spam my posts. Those are the three elements of the problem that need fixed, and culling old accounts won't help any of that. Paygating new thread and downvote/upvote will take care of multi-account abuse to either derep someone or uprep false accounts. Handling abusive posts/chats as one-offs will handle the rest, if the community doesn't handle the former via "report as spam" and the latter by simply blocking chat messages from unwanted users.
I can't think of any problem that blanket account deletion fixes, while not creating far greater problems.
You're absolutely right. I like what you said about "paygating." If you don't have a paid game on your account, then you're stuck at lurking in the forums. Buy a game, and you can post.
Of course, then you get the problem of some folks wanting to ask a question about a game before they buy.
Perhaps without a paid game, one report-as-spam deletes the post and flags that account as abusive and keeps them from interacting with the forum until a game is paid for? Or maybe a guest area could be made for those questions?
