A mistake I see a lot in my wanderings through left wing spaces, is people saying mistakes happened because of ideological impurity, or because that guy was a wrecker or whatever.
but by doing that -- by thinking you cut off the malignancy by ignoring those parts of the history, you lose track of why it happened in the first place. Which of the steps in the chain of causality caused that outcome.
In many ways the mistakes are the things you want to learn the most from -- no one can cause effects that large on their own, they were allowed, in some way, to do that action. they weren't prevented proactively, whether through social safeguards, organizational safeguards, or whatever.
Where things break down is, in some ways, what you want to spend the most time learning from, because people have made that mistake for you. Repeating successes is hard without a lot of context having parallels. Not repeating failures is much more reliable.
But often people instead go "oh well <thing we both agree is historical fact> only happened because <one guy was calling the shots>" and just completely remove it from their brain as a thing worth knowing because they go "I will not be like that guy" and not "How do we eliminate everything in the chain that allowed one guy to be able to cause that."
Like the comparisons of Catalonia's success to Russia's failure. Yes, true (for a few years, and then enduringly kind of sort of), but let's look at the context: Catalonia's productive centers were forcibly capital-injected and industrialzied by the fascists, the region covers a much smaller area, 32,000km2
whereas Russia was mostly agrarian and industrialized while fighting a civil war, is 17,000,000km2. They didn't have more than telegraph at the more remote cities until the 40s, and even then it was like a single line run to the headquarters of whatever bureaus there were.
which means managing all of your people gets much harder, and it's much easier to be deceived by only some hops in the line, where the big risk isn't so much lies going up the chain (though that's obviously a problem), but your contact to The Goings On editorializing while the people above you never asked you to do whatever it is you're being asked to do.
this isn't to say that the successes aren't something to learn from or focus on, and more that you can't generalize accurately without looking at the problems, otherwise you're trying to push through something with known failure cases that are actively being ignored.