I'd actually point out that HN is self-correcting. When you offer a comment that goes against the group orthodoxy, and you get downvoted to hell, all it takes is one additional comment pointing out that the downvotes were uncalled for, and that you do have a point regardless, and HN will self-correct. (Personal example: http://news.ycombinator.com/item?id=1661588)

Most times, however, people stop after they get unfairly downvoted, and think to themselves: 'well, that's group-think for you!'