The central reason why class reductionist ideas get so much currency on the American radical left is twofold:

1) American leftism was driven by self-guided book learning until 2015

2) The American right latched onto class reductionism and made it about culture and race

The primary way in which political ideology gets transmitted is via osmosis. You pick up the ideas from being immersed in an environment where they're common currency. Your family votes Socialist, or you joined Young Labor as a kid.

Apart from a relative handful of red diaper babies like Pete Buttigieg, there's no real way to get this in the United States. People become leftists through book-learning, generally.

But because this book learning is mostly self-directed, it's people reading books they learn about, which often means starting with basic Marx and moving on to Kropotkin or Lenin or (god forbid) Stirner.

The thing is, osmotic learning transmits what has been absorbed into the environment, which generally includes relatively contemporary theory. Book learning doesn't do so without directly reading it.

So people aren't going to read something like, say, Bayard Rustin or James Baldwin and absorb their ideas without a guide.

The majority of such guides are written by the cults that lie behind most tankie groups. So they focus on archaic shit and apologetics.

Occasionally you'll see something as modern as Edward Said pop up. But even Said is fairly archaic, in that there have been some substantial critiques of his theory of Orientalism from other Asian scholars.

So the end result is that people grapple with leftism from perspectives that tend to assume that things have been set in stone and decided, because you don't learn them as ongoing debates, and which often neglect other marginalizations.

The end result is class reductionism- the answers already exist, they're one-size-fits-all, and so we just need to apply them.

Currently, Rosa Luxemburg is a doll to draw out to castigate "succdems" or "liberals". If, perhaps, we looked into why the Spartacists launched their revolution when they did, and learned she knew it was premature but feared Bolshevik dominance of socialism, we might reconsider.