Markets are a transitional mechanism for marrying wholesale raw material production with industrial manufacturers. But once those relationships are formed, the industries integrate vertically and the market becomes vestigial.

Labor makes things possible, sure. But logistics as a rarefied branch of labor is both vital to an efficient supply chain and heavily influential over the flow of revenue within and between firms. The whole idea of the "middle man" as a parasite stems from the leverage afforded to extract rents in between extractive labor, industrial labor, and retail labor.

What's curious is that this middle-man position isn't even strictly capitalism. It can be (via the ownership of transportation capital), but it can always be entirely divorced from the ownership of the machines and real estate involved in production, by way of financing or licensing or administering traffic. The real sleight of hand that markets perform is to transform the concepts of corruption and price gouging, by way of legally or physical monopolizing certain trade routes and cash flows, into economic growth and (exchange) value accumulation.

This can still exist in a socialist economy. It is just categorized as economic loss rather than economic gain.