Basically, in the early 20th century, if you were a nationalist who believed in socialism, marxist-leninist style Communism would not have been a good fit. because it was a very internationalist ideology.
If you were a socialist, a nationalist and a virulent anti-semite, Marxist-Leninist style socialism became an even poorer fit. What you needed was national socialism.
On that TV interview of Lee Harvey Oswald, he is asked if he’s a Communist. He vehemently says: “No! I’m a Marxist-Leninist.” I could never figure out what the difference is. Or why he was so adamant in making such a distinction.