No doubt it started with the communists' MO of identifying groups of people who could be identified as "victims of oppression." But it has taken on a life of its own.
Once these people became more tolerated by society, they decided that tolerance wasn't enough. They wanted to spread their disease.
When we take a look around, we can see evidence of this everywhere, from K-12 schools and universities to entertainment to the military, and beyond.
Sexual perversion used to be identified as a mental illness. It appears that this is one of those mental illnesses that, if untreated, can develop into a psychopathic/sociopathic disorder.
Communists believe in strong discipline in the cadres. Their fighting forces are tough, e.g. Viet Cong and the PLA.