To its credit, HN actually has systems in place to deliberately discourage tit-for-tat commenting. First, it deliberately has no inbox to notify you of replies to your own comments, so you're much more likely to neglect to discover that someone has replied to your comment. Secondly, it disables the inline "reply" button for comments whose age is below a certain threshold, so that only power users who understand the workaround can actually reply to young comments. Thirdly, it has no support for navigating deep comments into dedicated subthreads like Reddit has, so instead successive comments will become narrower and narrower until eventually becoming literally unreadable (not actually sure if this one is deliberate, it could also be laziness, but the effect is the same).

As for bump-ordering, I lost most of my youth to phpbb-like forums, and I'd say they foster a mindset of even more obsessive interaction because not only do non-nested threads become impossible to follow if you're away for long enough, but keeping your preferred topics on the front page requires frequent monitoring and carefully-timed comments.