For thousands of years we have dreamt of flight. Icarus and Daedelus found to their cost that attempting it without the correct technological base or scientific knowledge was doomed to failure. We have even dreamt of flying to the moon in a sledge pulled by a flock of swans. Anticipatory consciousness is the constant companion of human desire and ambition but it must be married with the ability to actually do these things. To put it in Blochian terms, the warm stream of human desire must be underpinned by the cold stream of human capacity.
Socialism, whatever you take that to mean, is similar. All attempts so far to achieve socialism/communism have failed because they have essentially been attempts to fly to the moon in a sledge pulled by flocks of swans. It is a beautiful dream but we are nowhere near being able to realise it. Only now are we starting to see, through the development of technology and automation, the rise of the material base necessary for socialism. It still remains imperative to overcome the social limits of capitalist development and we must maintain the dream but for now we remain grounded in reality.