Congrats on being completely illiterate user.
Co-ops have socialized production because CAPITALISM has socialized production.
What makes co-ops unique is that they have socialized *property* to the extent they have socialized *production*.
And yes, in a market economy, co-ops will produce for exchange. But guess what we as Marxists now about Markets: they are self negating.
marxists.org
To Marx the issue was exactly one of socializing property, for he knew that capitalism would do the job of socializing and centralizing production to the extent that it destroys markets themselves.
Your first problem is that you've bought into the leftcom hysterics that the issue with capitalism is the firm, in which case you've just substituted the issue of surplus value for an even more retrograde humanist concept of alienation. If you read Marx over here you'd know that Marx had absolutely no qualms with co-ops as a unit. The most immediate problem with capitalist firms is a political problem, in that they produce capitalists. In a dictatorship of the proletariat, which is still capitalism, you will need to have proletariat control of not just formal political structures, but also economic and ideological structures. In a situation where the natural centralization of capitalism is not yet complete, that would mean cooperitization. Communism is the real movement that abolishes the present state of things, and in that sense, coops will absolutely be needed in the process of overcoming capitalism.