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?
So in terms of anarchism generally this is actually one of the hard problems of anarchism: What's the moral way to deal with resource competition?
I'd also like to point out that this issue of people going rogue and the study of anarchism in practice in the Maknovischia lead to the development of organizational platformism by Peter Arshinov as a direct response to how to prevent such things from occuring.
Makhnovischna was anarchism before platformism, which often had a lot of problems with keeping everyone on the same page.
The massacre you referring to is this. I'd suggest you read the history of it because it's not as clear cut as "Makhno loyalists murder innocent Menonites". There were steps taken before and escaalations and reprisals which is literally just the history of this time and place, but ultimately there was a massacre.
As for Jews, here's some reading, it's very muddy on if these things happened, but I would not be surprised if they did:
https://kehilalinks.jewishgen.org/colonies_of_ukraine/pogroms/ukrainianpogroms.htm
https://www.marxists.org/reference/archive/makhno-nestor/works/1927/11/anti-semitism.htm
https://theanarchistlibrary.org/library/nestor-makhno-to-the-jews-of-all-countries
As for Roma. I 100% believe it happened, and 100% believe nobody spoke of it ever again except through rumor.
Didn't Makhno himself work on developing platformism in his exile in France? I guess I wouldn't be surprised if what he wrote wasn't really taken seriously since, for most of the end of his life, all he seemed to do was alienate people and bicker until he died in squalor.
Anyway, I appreciate the conversation and the resources.