This is a really disturbing characteristic of Hacker News moderation. The people it happens to must feel like Bruce Willis in The Sixth Sense, when they realize it. Why not let them know??
I believe the idea is that it's for people who are legit trolls. If you let them know, they'll just create another account. But if they think people have just grown tired of their antics, they're more likely to move on to another site.
I'll be honest, and hope that my comments and honesty don't earn me the silent treatment. I am iteration 2 of a formerly silenced commenter. I learned a lesson or two and consider my comments more carefully before I post them, but it was infuriating to find out that 2 weeks worth of interesting comments weren't receiving responses because no one was reading them.
I am surprised you stuck around, to be honest. I'm not sure I would have, and I'm sure many don't. Could be argued that's the point, but it doesn't feel quite right.