"Stethoscope theory" is just a simplified version of the political compass.

Yeah, I can see that.

I've never seen this before, but it makes so much sense.

Who originated it?

I'd like to call out that authoritarianism can exist in all forms. Unless you literally define "Left" as "Anarchism." And even under Anarchism, strong men will crop up; the oxymoronic fact of anarchism is that it's the best environment under which cults of personality to prosper. You could easily have an authoritarian regime where you're sent to a Correction Camp if you use someone's preferred pronouns incorrectly, or decide you want to take a ride your fossil-fuel motorcycle. I think it's always an important fact to recognize that authoritarianism can arise in nearly every system.