[1]https://mises.org/library/economic-calculation-socialist-com...
[2]https://en.wikipedia.org/wiki/Socialist_calculation_debate
Marxism has nice slogans, but very little attention is given to the details of what is the value of good quality paper clips or whatever.
The assumption of perfect knowledge and that wise central planners can beat bottom up and local knowledge is wrong. It's interesting what a common assumption it is too. Even though government and large organisation inefficiency is often remarked about.
The assumption of perfect efficiency and that the free market magically leads to the best outcome for all is wrong. It's a very common assumption too. Even though the absurd level of inequalities or the ultra short-sighted plundering and wreaking of natural resources are often remarked about.
Even less attention is given to those (and more important things, like the environment) by liberal capitalism. The market will sort it all out.
Liberal economic theory says that there's no such thing as intrinsic economic value. See Diamond Fallacy. Optimal price signaling through a free market would be a necessary corollary. (And I think the Halting Problem could be used to prove that.)
Neither seem right to me, but Marxism definitely seems far more wrong. Nonetheless, concepts like dignity and justice wouldn't exist if labor and other activities didn't have some kind of intrinsic value, however indefinite or indeterminable. The vast majority of people in capitalist societies, especially those in ultra capitalist societies, and particularly Americans, believe in an intrinsic worth to labor. And human concepts such as dignity, justice, and "the value of human life" exist precisely to define what we perceive as intrinsic value. And perhaps that's what democracy is about--a hack bolted onto free market capitalism to aggregate (in a very poor manner) our normative assessments of different kinds of intrinsic values, and to pay those costs more optimally than capitalism alone could manage.
I think this is wrong. You're trying to derive human worth from economic value. You can't do it. (And even if you succeeded, it would be at the price of reducing humans to their economic output, which is really dehumanizing.)
Humans have lived and thrived without capitalist economies and with other priorities (from moral to religious and to civic duty) presiding over markets and profit for millennia.
The mere presence of commerce is not the same as capitalism (whose start is estimated at the 15th or 16th century, and it's total, often cancerous, spread over traditional communities in the 20th century).
The (lack of recognition of the) unconscious mind cripples socialism. Interestingly, Christianity and Buddhism both sneak it in, in one roundabout way or another; the next social movement needs to start right there, with the unconscious mind - tackling the conundrum of our deeper motivations including sexual selection. That might be possible. Sexual selection (often aided by our unconscious) overpowers every version of socialism so far. We need a version that can cope with that extreme pressure on human action.