This whole argument relies on the notion that the Marxists are the only opposition to fascism, but ignores what I said; the socialist movement never properly repudiated Social Darwinism. Literally NO ONE did. No one has since.
I do not deny the accomplishments of the USSR. Look where they wound up in the end, though. This is the problem in the end, because Communism didn't have a clear conception of what it was up against, which led their populace to be extremely susceptible to capitalist (fascist) propaganda during the 1980s collapse.
I am not talking about symbolic violence to feel better about myself. I am talking about systematically slaughtering every single Nazi and Nazi apologist and building instruments of state power to ensure that Nazis are completely, utterly wiped out, at a bare minimum. Surprisingly, Communists seem very, very spooked when you talk about taking control of institutions and constantly questioning them. This is a flaw in the Marxist-Leninist state, where it simply assumed the institutions work for the public good (when they most certainly weren't working in the historical USSR).
I really don't care about capitalism as a system. I don't give a shit about who owns what or if "the people" (which isn't even a real thing, just an abstract concept) own everything collectively. Even Marx would tell you that replacing the bourgeoisie with a collective abstract capitalist is not a great improvement and changes fundamentally nothing. Fortunately for me, that question is not particularly relevant to me. Given a rational look at the global economy and a central plan (and a central plan would be inevitable because the so-called "free market" has always been somewhat illusory, the world in practice has been run by powerful men for powerful men), unless there was some ideological rationale why the market system was to be preserved at the highest levels, it would be an obvious decision to abolish it and replace the market system as such with something different. You couldn't do that until you had a mechanism for central planning in the first place. However, by the time that was a technological possibility, the very people who would be in the vanguard of socialism openly abandoned the goal of political equality - and there was not really an argument to make against this scientific dictatorship, except that it was mean and shit, or that perhaps "the people" would fight. But "the people" never did fight, and Lenin himself understood that a spontaneous uprising of the workers was an impossibility. Indeed, "the people" and the so-called "working class" would tear each other apart even without prompting from capitalists, and it was comically easy to feed the working class narratives surrounding race and identity so their competition would escalate to absurd heights, producing the insanity we see today.
Literally the only reason we have capitalism in any recognizable form today is because a great deal of the middle class and the so-called "working class" actively want this unequal and stupid system. By now, capital should have centralized that state capitalism would be inevitable, and had the working class shown even a shred of class interest, it would have been possible (though not necessarily easy) to make the Social Darwinists tremble through a campaign of relentless terror. Far from that though, the normal American enthusiastically embraced the worst aspects of capitalism and their own culture, and only barely managed to pass measures of racial integration which should have happened 100 years ago. The Marxists had lost the initiative. They didn't get that Social Darwinism was the key element to fight, and that capitalism in its modern form was just the guise it took. Such a criticism, though, would necessarily entail a criticism of the USSR itself, from which any organization would have had to come.