In my experience, the best solution is have a core group of people come to a decision to use a platform that is just inconvenient enough that it doesn't become too popular, be that an irc channel, usenet, xmpp, etc. The old war of AOL vs. the rest of the Internet is still very much alive and well; it's just that it turns out, AOL wasn't the real enemy -- it was just one head of the hydra. The beast itself was user-friendly platforms in general.

And as anyone who's received the gospel according to BOfH knows, users are nothing worth being friendly to.

That HN isn't as bad as reddit is likely due to the minimalist site design in the first place. Throw a few rounded corners around the place and perhaps some pretentious cartoon characters and we could get there in a heartbeat.