People were always tribal. You just call out a group to be evil. And it takes just a little bit of propaganda and people will ignore any rational arguments and start harassing a group.

Witch-hunts (last conviction in Europe was 1944), jews, communists, americans, non-americans, all sorts of religious groups, ... history is full of that.

One thing that changed recently is that nowadays propaganda is very organized and well funded. I also think there was a pretty calm period for a few decades (but only in certain regions of the planet). In the cold war period the tribes were very fixed and the evil was always far away, so locally not much happened.