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?
Go browse /r/196 for 30 minutes. It might not answer your question, but it will probably teach you a lot about where online western leftists that call themselves anarchists are at.
E: I'll elaborate so that this doesn't come across as vague sectarianism. A lot of this is just kids transmitting vague vibes to other kids who are just learning that there's this entire world of politics that isn't just libs vs chuds. For the most part, it's scary, and if they belong to any marginalized groups at all, they probably really really want to avoid anything remotely fascist. Therefore it doesn't take long at all for them to encounter the logic that goes something like
"Marxist-leninists are just as problematic as fascists because Lenin and Stalin did x thing to y minority"
Can they afford to be skeptical of that? Can they afford to go have a serious look to dispel the lie there, when in their minds, going into ML communities is essentially the same as going to a fascist community?
Naturally, it doesn't take much convincing, your buddies who are also just very young and naive tell you who they don't trust and you take their word for it because it's just a dangerous environment everywhere, in general. Why trust anyone?
I still recommend you take a look and browse some comment sections for any post that's remotely political. Keep in mind they're all very young, many are queer, and they're very nervous. It's sad because it obviously would be better if they understood that the 'tankies' they talk about want to protect them just as much as even the most ideologically pure anarchist. But they're not ready to take our word for it for some understandable reasons and some very bad ones too.
Oof. Those poor kids on 196 are liberals. Just normal, everyday liberals. I thought it was a leftist sub.
Yeah, which maybe doesn't answer your question since you're asking about actual Anarchists as opposed to NATO larpers. Still, I don't think it's too unlikely that many of these people will grow out of the liberalism and start organizing with other Anarchists who know what they're doing.