That seems orthogonal to the primary concern of communism, which is to make sure no one goes without something they need, i.e. from everyone according to abilit

That seems orthogonal to the primary concern of communism, which is to make sure no one goes without something they need, i.e. from everyone according to ability, to everyone according to need. Lack of accounting for wants can make for an annoying, boring economic system, but that's a much lesser charge than the system is intrinsically genocidal. And if it's the difference between a boring system and a system where the rich oppress the poor, and many are forced to live miserable lives according to their less subjective needs like food, clothing, and shelter, then the former would be morally superior. Nor is it obvious why not accounting for wants would make an economic system less successful. I.e. if you have the best of the best bringing to bear the best technology and thought to improving the lives of everyone all at once, that seems superior to everyone trying to figure it out themselves. So, the 'subjective preference' objection does not seem very strong.