> Similarly, if a single product vendor and their customers form a community, then a free market of fulfillment companies can spring up to stock that specific product, and then partner with the delivery companies (who have their own networks) to deliver the package.

One thing that gets overlooked in this is returns.

One of the big draws of Amazon is easy returns.

Whenever you have decentralized fulfillment centers, returns become a huge pain, because the fulfillment center that is happy to take your money and ship you the product, doesn't want the liability of dealing with returns.