Hot take but Ur-Fascism is as popular as it is because it's a liberal idealist understand of fascism that was palatable to the postwar liberal world order. There is zero materialist analysis in it and Fascism can exist without most of the points outlayed and all of them can be present without fascism.

Fascism is a Political project intended to resolve the contradictions of capitalism without destroying it, often by wresting power from the Cosmopolitan Bourgeoisie and returning it to Industrialists. It typically rises as the result of growing left wing power, which is itself a reaction to the contradictions of capitalism. After WWII, you obviously couldn't have westerners having an academic understanding of fascism that included an understanding of the contradictions of capitalism, but you definitely could have a list of aesthetic and stylistic descriptors that were supposed to "define" Fascism.