Capitalism is a system of voluntary exchange in the market place. Enslaving client and tributary states isn't voluntary.

It's a natural progression that, without governmental intervention, would come about. Much like a monopoly. Or regulatory capture. Or acid rain. Or lead poisoning. Or company scrip. I mean.. when you essentialize capitalism to "a system of voluntary exchange in the market place", you knowingly choose to limit the scope of your investigation to the places that are clean. If you never look outside of the marketplace, you never see the larger processes that come about as a result of that, and which are inherently destructive on a systems thinking level. I'm talking game theory, human systems dynamics. Science.