What happens when you get rid of the four olds: Ideas, Culture, Habits, and Customs (旧思想, 旧文化, 旧风俗, and 旧习惯)? You are left with nothing but ideology to bind yourself to your fellow man.
You submit your mind, body and soul. Neither shared heritage, nor shared blood, nor shared culture nor familial bonds hold you to any. Only the power of ideology. And with nothing but ideology, you become a fanatic.
Perhaps you end up like those who last got rid of the four, who turned to cannibalism, murder, torture, maimings, blindings, and public humiliation. The Chinese communist party had to set their army on them to end the senseless killing.