It tends to isolate people into self-reinforcing communities, many of which have two things in common: They have an enemy that they demonize, and they admit no wrong.

Not all communities are like that, but when communities (and now that I think about it, especially ones where your comments can get some kind of point or reward) get big they trend towards that. Possibly because those behaviors are low-hanging fruit in terms of your comment earning points. Points feel good. No one likes to admit it but they do.

This at least gives people a moment to consider the other forms of entertainment beyond a screen? Maybe go outside? Interact with people? Play an instrument? Make some art? Go volunteer somewhere? Stand up? Walk around?

Other ones like Stormfront, MRAs and Trump?