Communist philosophy is somewhat anti-authoritarian. It's literally about putting the everyday people in power. It's often anti-democratic though. You have to turn to Nordic socialism if you want to bring democracy in, which was developed basically as a direct result of Stalin insisting that Soviet communism was the only communism, and you could either join their (violent, awful) communism or die.
Except, Lenin, Stalin, Mao, all wrote about how important it was to be self critical, how important it was to stay grounded in reality, to make reality drive your decision making and goals.
And then they all purposely and aggressively built themselves cults of personality with the express purpose of being just garden variety dictators. They surrounded themselves with boring "Yes men" by murdering anyone who pointed out the clear contradiction between their writing/philosophy/"theory" and reality.
There's a grand canyon between what they all wrote about, and what they clearly did. The closest they ever came was Mao being like "Whoops, a lot of people died, maybe it's partially my fault" but that sure didn't dissuade him, or make him change direction.
Meanwhile their hundreds of millions of insane, murderous followers had no qualms about such a contradiction, such a destruction of reality, because they had been so poorly treated for so long in the old system that all they really cared about was tearing it down (gee, sound familiar?).
A Cult of personality is toxic to functionality. It's toxic to any progress. It's toxic to productivity and success. It's toxic to competence. It's toxic to reality.