Two big things changed for me:
- Review was invented.
- The system deals with most of this stuff by itself.
From my personal viewpoint —that I seem to push every chance I can— I really think we can stop worrying about the old crap that we used to say would clog up the internet. These days I think The most helpful thing you can do on the site today is answer a post, and anything that draws people away from that focus isn't in the site's best interest.
I do think there is room for a new companion project to guide people towards stuff that needs attention. If I were building that today it would be far more focussed on linking people with questions they can answer, and getting them to review (and vote for/against) new answers within their expertise. A different, more productive sort of cleanup, if you will.