I live 25% of the year in a Communist country and have visited another Communist country. These daydreamers are right (IMHO) on a theoretical basis, but, in practice, Communism has a proven track record to leading to tyranny and Totalitarianism/Dictatorial regimes. Case closed. The dreamers can dream on but they need to lose their naive attitudes.
I don't agree with that they are right in theory. In order for the theory to hold and one reason why it doesn't is that one would have to conclude that human's by nature are less inclined towards stronger feelings of self than of others. I am aware of no time or place in history that this is the case. you would have to "change" human nature for this to occur, which if you believe in natural law then this is not possible. We are not blank slates to be molded into a good members of society based on the current whims of social science.