'Let a hundred flowers bloom, let a hundred schools of thought contend'
For the trick to work, millions of people had to believe the words meant what they said, even though the Party, within long memory, had never rewarded a contentious voice with anything except torture and death. Anyway, the suckers fell for it. The flowers bloomed, the schools of thought contended, and Mao's executioners went to work. The slogan had the same function as the Constitution of the Soviet Union, which Alexsandr Zinoviev telling defined as a document published in order to find out who agreed with it, so that they could be dealt with.
Reminds me, only a little, of when your boss, or your boss's boss, asks you what you really think of the new corporative initiative that you had no part in.