I really do believe there is a concentrated organized effort aimed at sewing that kind of discord in every online community, regardless of subject. Fandom has long been a place for people of all stripes to come together and bridge divisions that might exist in the outside world, and that is a threat to certain people in power who benefit from conflict.
I am NOT saying that all objectors to casting choices or “woke” story beats are paid shills. What I’m saying is that they are riled up and encouraged by a relatively small but dedicated contingent of actual paid trolls, working for shady troll farms, funded via dark money by those who profit from division.