One problem with your argument here is that we actually do believe that there have been proper socialist countries governed by communist parties, it's just that we understand that they exist under siege and aren't "pure" like so many western leftists require. They are absolutely proper, but there is excess and mistakes made by administrative bodies meant to protect socialism that exist out of a genuine necessity to fight counter-revolution and imperialist aggression.
Further, we can compare peer countries by how well each system has worked at satisfying the needs of the people, where socialism absolutely has superiority. Capitalism's death toll is higher both by rate and by magnitude as well.