Many of those extra-divisive platforms are still around in one form or another, and are likely bigger than they were in the past (thanks again to reduced barriers to entry). But a normal person can avoid engaging in those platforms entirely by just… not going on them.

Imo the danger of modern social media’s algorithmic feeds is that it draws in otherwise perfectly normal people, who would never voluntarily seek out the divisive content that gets promoted on their feeds. So now we have the worst of both worlds: platforms with violent political rhetoric are still highly available to those who would seek them out, and more average folks are drawn to seek them out by the “dull roar” that draws them in on the major social platforms.