As Marx said 'the limits to the exploitation of the feudal serf were determined by the walls of the stomach of the feudal lord' or as Rosa Luxemburg expands on this Marx quote in a passage I really need to find, most feudal exploitation was driven by a rational material need, food for the lord and his retainers, materials to build castles, maintenance of weapons and horses, etc which in turn are used to protect and seize more resources. Where as modern capitalists accumulate for the sake of accumulation, often unstably and at the expense of company/workers/resources, having cycles of boom and bust. This isn't a moral statement or recommendation on feudalism though.