Back-and-forth conversation isn't high quality by definition, it's just the baseline for not being bad enough to downvote. I think Hacker News wants the baseline to be some degree of exceptional.

Or just not boring. The guidelines state, among other things:

> Please don't use Hacker News for political or ideological battle. It tramples curiosity

https://news.ycombinator.com/newsguidelines.html

Reading yet another thread where commenters go back and forth on, eg how Elon Musk sucks/is awesome doesn't make for interesting reading because it's the same conversation that's been had before, and neither side is getting convinced by the other side's argument.