As moderators we can only judge comments according to the guidelines, and can only ban accounts if they repeatedly breach them. You're always welcome to email us (hn@ycombinator.com) about an account that has been continually breaching the guidelines.
That's where an ignore system is useful.
We hope that people will take the opportunity that HN offers, to be exposed to different points of view, if only because it helps you to become more knowledgeable and confident about your own positions. We understand not everyone is here for that!