Intellectual elites who are not teenagers living in Wyoming will often have other mailing lists, or even other live human beings, from whom they can get consistently high-quality conversation with none of the dreck that emerges when all of real life's checks and balances are disengaged.

This. I don't really have a burning desire for a general interest high-powered messageboard because I get lots of my general interest feedback from college friend/google reader hivemind/friends of friends/etc. And that discussion ends up funnier and more personalized, since my friends have more context about my questions and more shared allusions. When I need information they can't supply, I go to a specialized forum or use my own blog and facebook to put out a general call for help from people I may not know I know.