Geez, even the Wikipedia article on the term states that is Marxist. I think you are substituting "Marxist" with "as written by Marx."

Werner Sombart was heavily influenced by Marx. Regardless of how you want to view him. Read his entry on Wikipedia.

"Sombart, at that time, was an important Marxian, someone who used and interpreted Karl Marx — to the point that Friedrich Engels said he was the only German professor who understood Das Kapital. Sombart called himself a "convinced Marxist,"[1] but later wrote that "It had to be admitted in the end that Marx had made mistakes on many points of importance."