When the penny drops, we'll also attract a lot of spammers and scammers. Hopefully we'll have a way to taper this even better so Google will continue to respect our content.

What does help Google is they not only have to rate our content for indexing themselves, but they can use the poster reputation as a "new" indicator for indexing the posts if they want (and I hope they do use that)...

Reputation is really helpful for determining quality most of the time. (of course, not always.. but it is still helpful)