Ask Spammers: HN is an easy target, why are you bothering?
There's no captcha on anything and the site's markup is very simple. The vast majority of people on here could quickly spit out a bit of code that would spam HN; it's really not hard.
So why are you bothering?
Edit: Oh, so it seems some accounts have been hijacked too. Again, not tricky to do. Sad though that you have nothing better to do.