the quick and dirty answer is the userbase. it doesn't, at least right now, turn into digg/reddit/slashdot because the people who want to see a digg/reddit/sla

the quick and dirty answer is the userbase. it doesn't, at least right now, turn into digg/reddit/slashdot because the people who want to see a digg/reddit/slashdot are already at digg/reddit/slashdot. the community here likes how things are and has a vested interest in keeping HN like it is. so thats what they do, try and push out the bad where they can and promote the good.