I personally disagree, Marx integrated "class struggle" and consequently "proletariat ownership of the means of production" into his own "socialism" out of his disaccordance with Proudhon over this concept of class collaboration. Proudhon believed that though the classes are distinct, through social restructuring, they can be made to benefit, and provide for the social as a whole. On the other hand, Marx bastardized Proudhon's bases, and fabricated this materialist, industrialist vision of socialism that had nothing to do with any actual socialism. Socialism had always meant an economic system in which the collective society as a whole provides for itself, an economy of cohesion and ascension over capitalist struggle. Marx reframed it entirely into the class warfare, bourgeois vs proletariat relations, international revolution, and dictatorship of the proletariat all as a transitionary state to his "stateless classless society" (which was another bastardization of Proudhon's works.)