I’ve yet to be called a tankie.

Denouncing all existing socialism, present and historical, doesn't meaningfully put you to the left of western liberalism unless you're actively building socialism in another way.

I also think Marx could have gone a little harder

In what way?

I'm just not going to pretend that the few states that pretended to try communism didn’t also do horrible shit.

No communist party over a socialist state has claimed to have reached communism, nor do so-called "tankies" deny that there are struggles, flaws, and problems run into by existing socialism. These flaws come from existing in reality, and to use the ideal version of socialism, perfect, free from any blemish or struggle, as a club against existing socialism is a deeply western tendency.

It stems from the historic failures of western communists to actually succeed in revolution, coupled with the chauvanism culturally instilled in us westerners that tells us that nobody can be better than us, no matter how bad we are.