You're thinking of Stalinist/Leninist authoritarian communism, which certainly doesn't encompass all of left-wing ideology, only a niche. When Stalin came to p

You're thinking of Stalinist/Leninist authoritarian communism, which certainly doesn't encompass all of left-wing ideology, only a niche. When Stalin came to power, one of the first things he did was too purge all the anarchists and other non-authoritarian socialists. Thus most leftists despise Stalin and what he did. Mao, too.