[dredmorbius]

There are benefits and risks to intermediaries.

A chief problem with technically-mediated intermediaries is that rather than buyers and sellers being directly connected, they are connected through yet another, larger-scale intermediary. Amazon, eBay, and Alibaba are three such instances, and each has its own motivations and opportunities to distort markets.

Regulations, preventing the same intermediary from playing both sides of the transaction (in a pass-through mode, apparently, in the flipping case), fiduciary obligations, and of course, reporting, enforcement, penalties, and decertification for violations, are all highly useful steps.