I've never thought about it this way!

Have always thought of Amazon as "providing services / platform" to seller.

But from the reverse perspective, Amazon is outsourcing to sellers. Amazon is handling so much of the transaction, the seller may never actually see the product. Sellers are getting paid, primarily, for managing inventory risk.

The Amazon marketplace thing is genius because it hacks the metrics that Wall St likes. By converting inventory to a service, they transmute a liability into an asset. Amazon is a retailer without stock.

The liability (from an accounting perspective) of the inventory lives with the mostly small business sellers who don’t care as much.