Except it does matter about as much. They helped facilitate the Nazis getting power in the first place. They then continued the Nazis projects. The history shows that socdems align with and enable fascism. That Nazi Germany arising in the first place required the socdems to murder communists and create fascist militias. That is material to, and cannot be divorced from their later opposition to Hitler. You are acting like fighting against the Nazis exists in a vacuum, while aiding fascism does not and in fact is made null due to they helping mop up their mess.

They also do tend to side with fascists since before and after the big example, they have done so. We cannot make ww2 the singular case of fascism that matters. Socdem enabling of fascism in Latin America and elsewhere, or post-war Europe matters and is a stain on them that fighting the nazis for a time cannot clean away. You want to take some history and say that refutes the import or significance of other history before and after. The point is socdems can exist with fascism, they helped it become a thing in the first place. Fighting Hitler and then immediately protecting fascists' post-war does not somehow refute the point. It speaks to the ability of social democracy to facilitate fascism. It _can oppose fascism, but fascism also seems to rely on its help