Having played the game for about 200 hours now, I am going to say this: The people saying that Communism is OP in the game is very much a self-report rather than a genuine take on the game.

Thank you for a real report on the game. I never played Victoria 3, but I've played other paradox games like the HoI series.

I have had runs where I deliberately try to become Communist just for RP purposes, and I never have it work out. Either I almost get there and have a revolt to take the government back to an older Capitalist stance, or I just dont have any momentum to pull it off. Because why would my people do it? If anything, the games I have had CAPITALISM is the OP one. My people have frankly absurd standards of living, have been making tons of money, and have been living reasonable lives, and therefore are not open to radical changes in government (sometimes to the point that I cant even change minor laws because "Its fine as is").

You probably have to plan for communism from the very beginning, and orient your "build" towards it from day 1, and it probably doesn't actually start to steamroll until later on once you get all the exploity parts into place.