Well, when the historians are all socialists…….. :-(
Socialists will do whatever they possibly can to show that their infernally evil and failed governance philosophy is not infernally evil and failed. They constantly try to conflate European social democracies with socialism (NOT the same!) and in this case, pretend that fascism and nazism used something other than socialistic economic models.
No better term has ever been phrased than “useful idiots” for these people.