The difference between US 2020 and CR is a difference of degree, not of type, IMO. Also, would-be killers have to work their way up to the act - first darkly joking, then taking to the streets, then pushing, then throwing bricks. Each step is intentional desensitization.
you're the scholar, I'm just some guy who's read Wikipedia, but my understanding is that it started as marches in the summer of 66 and the crowd got murder-y later that fall ?