There were problems in the implementation of the cultural revolution. A major cause of the problems was the bottom up methods of justice but this was also a major part of its success. The goal was to preempt counter revolution by rooting out liberalism and in this regard it was a great success.
On the down side some people were wrongly accused and there were many cases of mob justice. Some people used it to settle scores. Some legitimate crimes against the revolution were punished far more harshly than deserved. Some times mobs lashed out in ignorance at things they didn't understand.
They broke 10 eggs to make a 3 egg omelet.
The people who escaped to tell stories however... There were many people who thought because they were well educated they deserved money and power. They were well educated because their parents had the wealth to get them educated before the revolution. Those people had the money on hand to flee. Those are the people who told the world about what happened. Those people claimed they were persecuted because of their education not because they had a bourgeoise mentality of class superiority.