HN was seeded with a group who had personal connections to YC or were hoping to be selected, largely using their own public identities. With the expansion of the community, the fraction of HN that has a personal stake in appearing intelligent and polite is much smaller than it was.
exactly - I attribute much of the priggishness of the HN community to this mercenary fact. Most folks who are obsessed with forging a strong online identity on HN are deeply invested in selling something to the rest of the group. I do not by any means disagree with this, but one of my first thoughts upon finding HN was how easily it might be lampooned. Everyone seemed to be self-promoting while trying to act casual. I will probably never have any kind of reputation here, because I spend my day either deep in thought at my computer, or reading/commenting HN. I don't forsee becoming a member of the web entrepreneur community, and because of my personality type I will probably never have a blog. But I know a lot.