Genuinely curious: if Amazon was very up front about this, and in no way pretended to be a neutral marketplace would this be allowed? Example: when a user signs

Genuinely curious: if Amazon was very up front about this, and in no way pretended to be a neutral marketplace would this be allowed? Example: when a user signs up to sell something on Amazon they're hit with a warning like "Amazon will always prioritize its own products over that of third party products, including future products that may be very similar to ones currently allowed in our marketplace. Be prepared to be removed for any or no reason, including because Amazon does not want too many similar products in the same category." Same question about Apple's app store.