> Nearly 20 years elapsed between the end of the Chinese Civil War which left the CCP in power and the commencement of the Cultural Revolution.

That’s not at all inconsistent with what the GP said. The point was that the impacts of thr Cultural Revolution depended on it being imposed top down by an authoritarian, unitary state with no constraints.

The cultural revolution was initiated by Mao because he was losing power and wanted to regain it. Even then it didn't happen overnight. It was preceded by a generation of buildup (in fact many of the violent perpetrators were young teenagers who were born after the Civil War had ended). And even if you start counting from when Mao initiated it, it still didn't kick into full swing overnight.