Economic Marxists explained the ills of society through the conflict between rich capitalists and the poor working proletariat. The rise of the middle class threw it a curve ball that it couldn't explain and it fell out of favor (outside of the Soviet union and American academia).
Cultural Marxism uses the same conflict between dominant class and under class to explain social pathologies in the under class. Thus, we all hear about statistics where under classes are not meeting the same performance as the upper class, with the implication that it is the upper class's fault. This is called "oppression".
So we know that women make less than men, but we don't hear much about how men are falling behind in college degrees and high-school education because this does not fit the Marxist narrative.
Furthermore, when there is an underrepresentation of an underclass in some desirable area, we take that to be de facto evidence of oppression (nobody cares that there are no female garbage collectors or miners). We all except the collective guilt for the sins of our class and nobody questions whether or not the Marxist narrative might just be fundamentally flawed.
Modern academic feminism and racial theories are based on Marxist models, which causes them to make many errors of reasoning IMO. There is also a lot of data that they can not explain. For example, racial Marxists have no problem explaining why some minority races do worse in school than white children (oppression!). But I've yet to hear an explanation from a Marxist as to how other minority groups (Asians) do way better than white children.