Marx was writing in Victorian London, somewhere that was racially homogenous. The distinctions between people were all related to wealth and social class. If he lived in modern America he would certainly have talked a lot about race and gender instead. His worldview was essentially an apocalyptic one which saw the world divided into oppressors (the bourgeoisie) and the oppressed (the proletariat), in which all injustice came from this unnecessary division and in which the oppressors would be forced out of existence through revolution. He predicted that the result would be a utopia.

DiAngelo bears some striking resemblances to Marx, and not only in terms of her binary, literally black and white worldview.

Marx was a wannabe academic who devoted his life to writing books about the oppression of the working classes. He lived off the largesse of patrons and supporters, notably Engels, but also his own family, and thus never had a "real" job in the sense the working classes would have recognised. DiAngelo is an actual academic who derives the majority of her income from preaching to her political supporters, although she cloaks it in the language of "training". A major criticism of Marx both in his time and after was that he had no real idea of anything he was talking about, for example he wrote extensively about factory conditions in England but had never actually been to a factory and in fact rejected his friend Engel's invitation to visit one. He wrote extensively about the working classes but had no working class friends or acquaintances beyond his housemaid, whom he abused terribly. Instead his knowledge of the world came entirely from reading books and thus ended up often distorted or wrong, for example, he had a habit of criticising factory conditions from decades earlier which had in fact been fixed via British regulation - something that in his world view wasn't supposed to be possible.

We can see echoes of all this in the way that DiAngelo (a white woman) and her followers (almost all whites) are obsessed with systemic racism, even though genuine systemic racism of the form "blacks may not enter this bar" was wiped out decades ago in the USA. Like Marx, they often rely on sleight-of-hand to argue the problem is still present and unfixable without enormous social change.

Marx's books were filled with impenetrable academic language and terms that nobody outside his small 'intellectual' circles would have understood, e.g. the term "proletariat" which had fallen into disuse since Roman times was revived by an obscure Swiss economist and then adopted by Marx, with nothing in between, thus only a tiny number of people would have understood this word. Marx's writings are still largely unintelligible even to modern readers well acquainted with his ideas. Consider this passage:

"The weapon of criticism cannot, of course, replace criticism of the weapon, material force must be overthrown by material force; but theory also becomes a material force as soon as it has gripped the masses. Theory is capable of gripping the masses as soon as it demonstrates ad hominem, and it demonstrates ad hominem as soon as it becomes radical. To be radical is to grasp the root of the matter. But, for man, the root is man himself."

The language is English but trying to parse insight or meaning from this paragraph is very difficult. Likewise "White Privilege" and the many similar articles are filled with text that feels like something written by GPT-2 to anyone outside the tiny circle of academics in that community. Here's an abstract from an academic paper of the genre (not by DiAngelo but someone very similar):

https://journals.sagepub.com/doi/10.1177/1367549420985852

"Using #MeToo as a starting point, this paper argues that the cultural power of mainstream white feminism partly derives from the cultural power of white tears. This in turn depends on the dehumanisation of people of colour, who were constructed in colonial ‘race science’ as incapable of complex feeling (Schuller, 2018). Colonialism also created a circuit between bourgeois white women’s tears and white men’s rage, often activated by allegations of rape, which operated in the service of economic extraction and exploitation. This circuit endures, abetting the criminal punishment system and the weaponisation of ‘women’s safety’ by the various border regimes of the right. It has especially been utilised by reactionary forms of feminism, which set themselves against sex workers and trans people. Such feminisms exemplify what I call ‘political whiteness’, which centres assertions of victimhood: through these, womanhood (and personhood) is claimed to the exclusion of the enemy"

Not only does this text have the similar highly abstract, rambling feeling of Marxist writing but it even uses the same obsolete Marx-only words, like "bourgeoise"!