What historical communism proved, what past and modern capitalism confirms, and what leftists in the mould of Varoufakis blithely ignore, is that the concentration of power is a source of mischief, abuse, corruption, no matter the initial motives for gathering all ultimate authority in a single locus. Take it as a given that there will be competing forces, recognise that corruption and power go hand-in-hand, and do not expect the human kind to behave much differently than other pack animals (the idea that humans are higher beings is another hubris of ours, a form of anthropocentrism).