Reaching only the Dictatorship of the Proletariat stage and not the Withering Away of the State stage doesn't make it not communism. That every nation that has tried has never gotten past stage 2 means there is a problem with the ideology. That every communist experiment to date has come to the same brutal and oppressive results also speaks of a problem in the ideology. If an experiment repeatedly fails, you look at the hypothesis to see why; you don't claim that those weren't true experiments.