Part of the problem with identity politics, which incidently is practiced across the American political spectrum, is that it is a retreat from having anything meaningful to say about the economic system in which we all live, either where it is going or how it can be understood so that non-intellectuals can have some comprehension of what is determining their fate. I think most Americans will listen to a reasonable argument so long as it is not part of some kind of "I've got all the answers" thinking.
Part of the problem with people who identify themselves as "leftists", "socialists", "Marxists" etc. is that they don't have anything really to say to people, they can't answer even the most basic questions about what is going on in society.
For example we have a large group of self-identified leftists who still believe that socialism existed in the former Soviet Union. Most Russians also understood that socialism existed in the former Soviet Union and they rejected socialism as a result of their experience with it. Workers here also rejected socialism as it was presented to them by the American Communist Party as existing in the former Soviet Union. That leaves a large number of American "leftists", "socialists", and "Marxists" alienated from the very people they presume to have something to say to.
The retreat to identity politics in this atmosphere of alienation from the masses is quite natural. Otherwise one would have to look clearly at one's prejudices and assumptions and undergo a painful amount of basic testing of ideas against reality.
Incidentally it was always my understanding that any claim to "scientific analysis" had to be able to explain reality and had to be proved empirically by events. So ask yourself which "leftist", "socialist" or "Marxist" analysis explained the fall of the Soviet Union?
-PF