unite the workers of the world

Too specific. Think of it like this:

Marx believed and professed that there were, largely, two groups of people. One with property (to him this was capital) and one without. For him, those with property i.e capital (bourgeoisie) engaged in a system, capitalism, to exclude others from obtaining this property that afforded them the better life.

When you think of it this way, it absolutely is still alive and well and used knowingly and unknowingly in a myriad of ways.

For example, whiteness. Those with this property i.e. whiteness engage in a system, white supremacy, to exclude those without this property from enjoying its benefits.

You can apply this framework to anything and it's exactly what they're doing. That thing is Critical Theory, and that is Marxism.