I think there's some misunderstanding here. Amazon is a massive logistics system. The retail storefront is a tiny part of what Amazon is today.
AWS exists because Amazon needed to solve an internal data handling problem in order to solve their logistics problems so that they could scale up. After building that system, they started selling it as a product to other businesses. The point being, Amazon's real success is based on providing business-to-business services. The retail website is the tiny public-facing bit, but it depends on the rest of the organization structure in order to operate properly.
What you're proposing is more like an eBay alternative, where the system is basically just the storefront, and the sellers listing products are responsible for their own logistics. eBay still provides dispute resolution for buyers though, and that's hard to achieve without some centralized control.
There's also the legal problems. At some point someone will use such a system as a silk road - probably sooner rather than later. Whoever is administrating and hosting it will be liable for criminal activity in the countries where the crime occurs. It will not end well.