As I said, communists/Marxists. Marx was an "authoritarian" socialist, and by far the largest strain of Marxism in the world is "Stalinism," aka Marxism-Leninism, the second largest probably being Marxism-Leninism-Maoism.

And, as I said, it's derogatory, which suggests the people saying it view such strains of thought as "tyrannical." So no part of your correction was at all necessary.