The problem is that once inequality creates political advantage, you have a political system which is inherently unstable. There's a feedback loop which promotes the influence of selfish sociopaths and narcissists at the expense of everyone else. Any system that does this will fall over, for the same reason that you can't balance a pencil on its tip.

You can't solve this with Rawlsian argumentation. You can only solve it by building policy around some other set of feedback loops - ones which promote stability and collective rather than individual progress.

If you want to see how democratic a system is, don't waste time on rhetoric about votes, democracy or ethics. Look at the feedback loops. Use them to see which behaviours and attitudes are promoted and rewarded, and which are punished.

You can then see that (e.g.) NCE is inherently disastrous because although it's surrounded by a fog of rhetoric about freedom, choice, democracy, and the rest, and although it pretends to promote stability, it's based on feedback loops which explicitly reward greed and selfishness.

Soviet Communism was disastrous for different reasons. After Stalin created a monster, the feedback loops promoted conformity, dull political cunning, and lack of imagination.

And so on.