First, thank you for an informative contribution. But…

“if, as a postmodernist (or as anyone else), you don’t accept the highly metaphysical theory of surplus value”

I am no Marxist, but I don’t see how anyone can characterize the concept of “surplus value” as being at all “metaphysical.” In Marx it is an attempt to describe the remunerative result in a productive process in which all employees contribute to total revenue but only one or a few a self-interested persons decide how remuneration is to be distributed within the firm. Perhaps you meant ‘esoteric’?