Amazon - often picks all the suppliers, and lets the buyer decide which they prefer.
Also - they deal in finished (consumer) goods. There is a whole lot of coordination before that stuff gets assembled and ready for Amazon or one or their marketplace suppliers to ship it.
Maybe they've integrated the demand chain logistics, but not the integration supply chain. And they don't dictate that consumers get to purchase one and only one brand of whatever product (like peanut butter).
Re:Jeff Bezos’s Master Plan
by dredmorbius on Sunday October 20, 2019 @03:58PM
(#21306655)
Amazon b2b: https://www.amazon.com/b2b/info/amazon-business
Hayek's basic premise was that national-scale central management was impossible. Amazon and other megacorps put paid to this.