That assumes that upvoting and flagging are a reasonable feedback loop for on-topic-ness. They aren't. Most stuff that's either on or off topic doesn't get up

That assumes that upvoting and flagging are a reasonable feedback loop for on-topic-ness. They aren't. Most stuff that's either on or off topic doesn't get upvoted, so there's not much data there for positive reinforcement to establish norms. If you look at the "new" page, most of it is on-topic at any given time and most of it will never see the front page. Flamboyant titles probably help set things out from the pack, but don't improve the quality of the site. I see meta-threads like this as the commit-list-flames of the OSS-world. You screw up the repository, and the crotchety regulars tell you how and why. This both educates and triggers social cohesion-fu, which maintains some level of quality. If we imaged, for instance, that we were to remove those flames from the OSS world, and suddenly, shitty code would be silently disappeared by the invisible hand of coding goodness, I don't suspect that would be nearly as effective. People would keep committing bad code. Turns out telling them why their code is bad teaches them to write better code.