To argue that Socialism means something other than a command economy, you have to disagree with all the major players that were actually responsible for defining Socialism to begin with. I choose not to do that and I accept their elaborate, very well documented descriptions of what it is. And I'm not referring to associationism or the cooperative movements, I'm talking about Socialism.

Invoking Mussolini this way is a particularly telling example.

So is Hitler. Why not just simplify your argument to "The Nazis were National Socialists. Check and mate!"

Its worth noting that your examples include:

(1) two members of the same early subset of socialism (Marx and Engels) and two later people known for involvement in the same descendant of the form of socialism embraced by the earlier two (Lenin and Trotsky), and

(2) two other people that aren't recognized as having an important involvement in anything recognized as a branch of socialism, though one of them was involved in a political party with "socialist" in the name (Hitler and Mussolini).

Its hardly a broad sampling of "the very people that were instrumental in creating and spreading Socialism and its intellectual foundations to begin with".