Although pg might not allow it (just quite how I do not know) if the level of abuse rises to a significant level for long enough people will leave. So for examp

Although pg might not allow it (just quite how I do not know) if the level of abuse rises to a significant level for long enough people will leave. So for example a couple of trolls go on the rampage (and it doesn't require many people, just a few with far too much time on their hands) for a week you could lose quite a few members and when the trolls leave or are banned not all of them will come back. The abusive behaviour needs to be stamped on hard and fast as others might just get plain fed up if nothing is done about a troll and leave. And it is not just abusive behaviour, just imagine that on every post someone posted the (ir)relevant xkcd / penny arcade / dilbert link to go with the post and the discussion gets flooded with chatter about the cartoons. You could completely ruin HN without a single swear word or sexist / racist / whateverist remark.