i think the problem is people aren't wired correctly for this option, which wasn't available in a high-bandwidth edition even 20 years ago, to be safe for societies in the long run. the dopamine-driven positive feedback loop that happens in such echo chambers cause a runaway reaction of radicalizing the opinion of the whole bubble to the point where it's a religious issue when confronted about it. you almost admit it yourself and correctly diagnose that HN is also like that.
no idea about that psychology stuff. i heard those words before :)
Echo chambers obviously happen even on sites with larger userbases (follower groups on Twitter, particular subreddits, etc.).
I don't know if having walls built into the system helps or hurts. Or does nothing at all. Ultimately, I don't think it matters since people are going to organize into some form of group no matter what.
no idea about that psychology stuff. i heard those words before :)