Regarding Nationalism and Socialism

Beside all the killing and wanting to take over the world, and all the dreams of ethnic cleansing and the other Eugenics nightmares there were two main problems with National Socialism. The first was nationalism. The second was socialism. The first can be rendered harmless if, like say in the US, you have a country and government and way of life that did not include all those evil things I just mentioned. The second is still evil.

Somehow the German left got this in to their head. Even though the problems with nationalism were obviated in the way I just mentioned, ie, they do not have genocidal maniacs running their country, there is still something wrong with nationalism. However socialism is still good. I just cannot figure out these do-gooders. Are they all so stupid?