Because if you think critically about that concept for a moment it falls apart. If people didn't have to work to earn wages in order to survive and simply had their needs provided by society there would be little incentive to work, thus few would work, and thus workers would have to be compelled to work by the state. Thus slavery. It solves no problem.
It seems strange that for the vast majority of human history most people were not wage workers and yet now we're positing that there is absolutely no other way to organize a society.
Prior to that you had feudalism where you farmed land and shared the spoils with a king, prior to that we simply murdered the unproductive and socially unacceptable by removing them from the village. So far this seems like the best option.
