The problem with the wealth-weighted-value that gets optimized by capitalism is that the gini coefficient tips the optimization process from being about doing what other people want to being about doing what rich people want. Rich people mostly want to get paid for being rich, of course, so they pump assets to increase their wealth. Their weight goes up, the objective function pumps assets harder, their weight goes up, the objective function pump assets harder... and gini heads to 1 and you return to a palace economy.
A note of optimism: we've been here before, shortly after the industrial revolution. We've fixed this before, even though Marx predicted that we couldn't. We should all be trying to figure out how to make sure that next time the USA gets neo-Roosevelt, not neo-Hitler or neo-Lenin.