It's all statistics. My suggestion is that HN is supposed to be a better filter than just ignoring bloggers who infrequently post good things.

And this off to a long digression about the opportunity cost of reading the bad articles vs. the benefit of reading the good ones and on and on...

But yeah, it's not perfect. If anything, if there were no articles you disliked on the front page, then HN would probably be too conservative a filter.