Opium Wars, Rape of Nanking. Things had been pretty hardcore for the Chinese for quite some time when Mao took power.
People that take power in those kinds of environments rarely trend towards genteel treatment of their political enemies in the peace that follows.
I don't think the "Down to the Countryside Movement" was what the Red Guard were expecting as their reward for supporting the revolution.
The current agitators in the West need to remember that the latitude they currently have to dissent and protest isn't likely to exist after the actual revolution.