I've known two people that have been hell banned here for single one-off comments. In both cases it had to do with supposedly disrespecting prominent Silicon Valley big shots that are worshiped on HN (eg in one case it was about Chris Dixon).

In my opinion the fastest way to get banned from HN, is to say anything negative about the elites. Even if you're just criticizing, that'll be enough to do it.

Zero accountability indeed.