> there's a far more positive community when people have a shared interest

Even old fashioned web forums and email listservs are still thriving in some niches and work this way.

I think reddit fails here because it's too frictionless. Requiring a little bit of intentional action to join or subscribe keeps out a surprising amount of drive-by trolls.

HN is pretty big now and has its share of trolls and bots but because it doesn't use social media accounts it's not nearly as bad as Facebook or Reddit.

How does reddit use social media accounts?

is it because I was young? I still believe phpbb forums were the best!