Access to information and easier communication will do that all by itself. When I started using Twitter I followed lots of people of differing political viewpoints to avoid an echo chamber. It was a hideous reminder that there are many, many people who genuinely hate me and what I believe in and that there are an incredible number of idiots with strongly held wrong opinions and no grasp of basic economics and politics. People hating each other because they have radically different views, priorities and goals is normal. The flattening of opinion that happened between the birth of radio and broadcast tv and that of cable was the result of a determined effort to control the narrative, not something natural.

I certainly see the polarization and radicalism but am unconvinced that FB was critical much less a “cause”