Alright I'm going to try and actually effort post for once
>Class is inevitable and natural
It may have been inevitable. The material conditions of the first civilization may have required class. For example Mesopotamia. You have rivers that would flood at random moments and since, ofcourse, science was not a thing, people blamed the gods. So you need a group of people to be able to talk and reason with the gods creating a class of priests to do just that. And since they had the power with the gods, they were also the kings so the city they inhabit since they speak for the god that city represented. But Today, class can easily be abolished, we have no need a man to speak with gods, there is no reason to have a group of people to own capital while everyone is reliant on them for survival.
Class isn't natural. Humans of the Paleolithic Age had no class, everyone was a equal participant on their clan. Since this the beginning of human history, this would also be human nature at its rawest so we can conclude that class is natural and only came about in beginningbof civilization when human relations grew more complex.
This is a fair criticism. A main point made by more Libertarian Socialist tendencies is that they point to the flaws of the USSR especially in their bureaucracy where a politician in Moscow can dictate how a factory in the Uzbek Soviet Republic will operate despite not understanding the material conditions due to unreliable economic data so common in the country's history. But then again, the material conditions of the country needed this crypto bourgeois class since feudalism had only been established 50 years before the Revolution.
That's why we use Dialectical Materialism. Marxists analyze the material conditions of a period and then arrive at a synthesis. Lets use France. There is a Aristocratic class who own the land which there serfs work on. There is also a bourgeoisie who profit mostly off the trade on commodities. These two classes would contradict each other as the Bourgeoisie would question the Aristocracy's and their King's legitimacy during the enlightenment. This eventually lead to the French Revolution where the Bourgeoisie overthrew the King and abolished Aristocratic rights establishing a economy based on the trade on commodities since it favored the bourgeoisie merchant class rather then the land owning aristocrats.
Class struggle is the basis of history. Did the Celts and Latins have perpetual conflict in the Roman Empire. No. Was there big conflicts between African Slaves, Amerindians, White Spaniards and Mix raced people in the Latin American revolutions when they overthrew their Colonial rulers. No. Those were started because the Latin American bourgeoisie felt threaten by trade laws imposed by the Spanish Crown. An example of class struggle.
Wars of Imperialism have been used historically been used as a way to unite all classes in a common goal in lets kill people of that other country instead of the guys who are sending you to kill those other people. Remember how the Social Democratic Party of Germany was radical pre war but then throw that out that window in favor of the war. Thats why Liebknecht created the Spartacus League. Unite the Social Democrats that opposed the war.
We don't see a rejection of Marxism as a failure of the people. We see it as the ruling class try to skew Marxism away from Proles such a easy lies such the famous gorillions nonsense. See Cultural Hegemony and Supersctucture.
>escape moral culpability for their actions
A common misunderstanding of us that we're all the same. Come here for 10 minutes and that's instantly disproven. There are many tendencies here such Marxism Leninism, Left Communism, Anarchism and a bunch of others. We all have different degrees to which we respond to this "moral culpability". A ML might say it sort of happened based on material conditions and an Anarchist might say it show the flaws in State Socialism. I am to assume this anon is a Nationalist. So how does a Nationalist account for bad stuff done by their country. He says that was in the past but where different now. So how does that differ from a Communist saying something along the same line.
I wouldn't say it rethinks Marxism. Marcuse had worked with the US State Department and Office of Strategic Services. (Proto CIA). And he later rejected class struggle it self and never really tried to update Marxism. Adorno and Horkeimer where influenced by Marx especially their criticism of enlightenment and the use of the culture industry but never rebranded Marxism in a different way.
>Marxism is very complex
Anon just admitted he doesn't understand Marxism.