Earlier quoted context omitted.
Who are you talking about?
Karl Marx. And I see the point the parent is making, although that's probably more of an issue in the USA than in Europe for instance. And I do agree that it's a shame because the writings of Marx are extremely interesting and deserve to be studied and discussed even if you don't believe in socialism and communism, it's really about economy in general first and foremost. Dismissing this important ground-breaking work…
Nowadays, it's sort of a generic derogatory epithet by the right for anything that they disagree with that can't be ascribed directly (even in a very loose view) to actual economic Marxism, because everything bad must have “Marxism” stamped on it somewhere.