Nerd stuff aside, no voting system for socially significant decisions needs to scale to the planet. Democracies don't (or rather, shouldn't) scale. e.g. if the US and China or India formed a democratic superstate, the effect would be that the US would just become a vassal of the much larger entity.

If larger or more powerful groups want to impose their will on smaller ones, they can go ahead and unilaterally do that, and own their behavior. Doing it "democratically" is just victim blaming.