You've glossed over the most important fact: we banned that user, as we've banned everyone we know of who's posted like that. If there are other accounts that you think have been posting egregiously, you're welcome to let us know. That would be a way you could actually help HN. But your insinuation that we allow shit like that to fester here is insulting. There's nothing we've worked harder at, often—speaking personally—to the edge of what my system can tolerate.
It's interesting, also, that you've had to reach for an example from 2-1/2 years ago. Nearly 7M posts have appeared on HN since then. That suggests that this community and its moderators are not as you say.
It's impossible to operate a large, anonymous public internet forum where no horrible comments appear. Demanding the impossible is not helpful. Armchair snark about how moderators fail to achieve the impossible may feel like a harmless internet pleasure, but consider the impact it has on the people you're attacking here. This place is fragile. The people who run it are under intense, unrelenting pressure. Kicking us in the gut is not a great idea if you don't want to make HN worse.
We can't control what people post, since anyone we've banned can just create a new account (and many do). All we can do is react to what gets posted. If there's some obvious thing we can do to dramatically clean up the site that we're not currently doing, I'd love to hear about it. But when you say that HN is no better than the worst of the internet except for the un-merit of a scum of politeness, I feel like you're trivializing the problems we face. Nor can I take that seriously, because it's patently untrue. If HN is no better than that, our hard work is useless—is that really what you mean to argue? And do you really mean to slag people who are trying hard to prevent a site you've been using daily for years (and for free) from degenerating into sludge? Because that's how your comment lands with me, and when we get that from experienced HN users, it makes me want to throw in the towel.
Nobody said civility would solve everything. It is a necessary condition, not a sufficient one. Incidentally, I've been thinking for the last few months that we should take that word out of the site guidelines. Its only visible effect seems to be that people get to accuse us of having that dumb idea about civility. There are deeper words we could use, which I would be happier to be associated with.