I believe marketplaces could/would form, acting as aggregators for sellers to list and promote their goods, and for consumers to go shopping.
In the 2020s, the web is nearing a level of criticality to a functioning society as the neighborhoods, towns, cities we access it from. Those physical properties are heavily regulated and with good reason.
On the first point, I’m referring to a new kind of marketplace. Essentially something made explicitly to address the problem you mentioned. A generic marketplace that enables the discovery of new products/markets is conceivable.
Regarding regulation, physical spade is definitely one part of it. But the public is also generally against nuisances, including too many advertisements. It’s an imperfect analogy, but not too far off.
