Personalized Political Spectrum

I don’t consider tankies lefter than me.

Seriously. Tankies are authoritarians who consider themselves leftists.

Authoritarian / libertarian is on a completely different axis from left / right, no?

Only on the political compass, which uses a definition of left vs right that a lot of leftists disagree with. Really, the entire history of "left wing" politics has been about questioning and dismantling authority. The terms "left wing" and "right wing" come from the French revolution, when the people in favour of simply reforming the monarchy sat on the right side of the room, while the people who wanted to fully dismantling the monarchy sat on the left. A lot of more modern leftist thought is about questioning the power that capitalist businesses have.