The National Socialists certainly opposed the 'Stalinist' Communists, but they were hardly enemies of Marxist theory. Strong central government control over means of production and government regulated distribution of rewards based upon a government perceived 'fairness' were intrinsic to the Nazi message. Neither free-market nor capitalist.
So, despite opposition to the 'Stalinist' Communists and Social Democrats, the Nazi's were merely a third socialist alternative.
They were fighting for the same hearts and minds.
In 1930s Europe, as well as amidst most intellectuals in America at the time, socialist alternatives were considered the ONLY alternatives. Constitutional republics—even as early as Republican “Progressive” Teddy Roosevelt (1900) were considered passé—especially among the educated classes.
Not until the shock of the truth of the barbarism of Communism came out in the 1950s (after we knew the barbarism of the Nazis) did conservative-seriously-constitutional thinkers arise who once again believed in classical liberal principles and capitalism. 100 years ago-—intellectually—was a much worse for liberty, than today.