Particularly be because, as Piketty shows, again and again and again, amassed concentrations of captial bend all politics to it, with seeming certain inevitability.

Not at all. They're largely orthogonal to one another, one being about market access and the other about factors of production. In many ways they're even antagonistic; a system that asserts the primacy of capital over labor and treats it preferentially reduces access to markets for those whose primary contribution is labor (which is most of us). The two only seem hard to distinguish or disentangle because people are conditioned not to think too hard about the difference.