you can be deeply offensive on hn if who you are offending is people outside of what hn considers to be its own audience. hn posters will defend the harm their software does to society all over town. people on this site care only about decorum; the syntax of kindness without the semantics.
That is deeply not the case, and if you or anyone finds examples of it, you should let us know at hn@ycombinator.com. If people are being cruel and not getting moderated, the likeliest explanation is that we haven't seen it, because we don't come close to seeing everything that gets posted here. Oh and we don't give a fuck about swearing.
The generalization you're making is so false and so mean that I would call it a slur, both of this community and of the people who work on it.
Can you honestly go look through the comments of any post touching any of those issues and call them kind? It's one thing to say it's out of scope for moderation because they keep it civil and calm. But to say the cruelty isn't there is to choose not to see it.