Separated websites make it very hard to bring along your own networks of people. If I share stuff on Twitter or Instagram when I share it I "bring along" everybody who is following me, and if they share it they bring along their people and so on.

Some sort of "distributed comment section" that you bring along when you visit a site could bridge this gap, but I haven't seen anything event remotely ready.

I mean technically you can have a chat with your friends and share a link. But that doesn't really have this "live", "organic" feel of a public square.