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 it’s a couple of things
Western chauvinism inculcates “those are bad countries doing bad things in a bad system” which takes a lot to unlearn.
Authority can and always is abused for corruption and has been abused for corruption in communist systems, which in part justifies the charge that any system with structural authority will be abused for corruption.
Angst vibes lead to a “fuck every system” attitude.
By standing against all authority structures that actually exist or have existed, they are immune to criticisms based on reality, so I think to a degree it’s a stand you take when you want to take a stand but don’t want to accept that reality is always flawed.
Communist states are often militaristic which sits uncomfortably close to nationalism.