Edit for clarity: I'm not asking why the Tankie/Anarchist grudge exist. I'm curious about what information sources - mentors, friends, books, TV, cultural osmosis, conveys that information to people. Where do individuals encounter this information and how does it become important to them. It's an anthropology question about a contemporary culture rather than a question about the history of leftism.
I've been thinking about this a bit lately. Newly minted Anarchists have to learn to hate Lenin and Stalin and whoever else they have a grudge against. They have to encounter some materials or teacher who teaches them "Yeah these guys, you have to hate these guys and it has to be super-personal like they kicked your dog. You have to be extremely angry about it and treat anyone who doesn't disavow them as though they're literally going to kill you."
Like there's some process of enculturation there, of being brought in to the culture of anarchism, and there's a process where anarchists learn this thing that all (most?) anarchists know and agree on.
Idk, just anthropology brain anthropologying. Cause like if someone or something didn't teach you this why would you care so much?
I think most self identified anarchist these days don't arrive at anarchism because of some deep introspective journey. They leap into it based on inherent biases against ML states. They learn all about the evils of capitalism and decided to be against it but still believe all the bullshit about the USSR and China. I don't think it's people being educated or pushed to be anti-communist more not being pushed to actually study communism and look at AES critically through it's own lense. In which case they are going to default the cultural western view of seeing them as totalitarian and therefore evil. They just sort of default to it as it feels right.