Genghis Khan's desires were ultimately subject to phsyical constraints and diminishing returns but capitalism removes natural limits because accumulation can be infinite

Weber paraphrases Marx as appreciating that “the limits to the exploitation of the feudal serf were determined by the walls of the stomach of the feudal lord.” Under capitalism, on the other hand, we have profit-oriented commodity production. This means that neither “stomach walls” nor any other kind of natural limit impose themselves: accumulation can be infinite, and since everything is tradeable with everything else, the capitalist not only can but must (in order to compete) accumulate without limit.

from https://redsails.org/why-marxism/