I understand that this sucks for specific merchants like you (or OP's Viahart), but if you consider it holistically (across all merchants and products in a category) I think it's a lot less sinister. Imagine some vendor sources a cheap POE KVM from Alibaba, lists it on Amazon for $250, and advertises against your brand keyword, hoping some people looking for your stuff will think "hm might not be as good but it costs half as much, I'll give it a try". If Amazon knows that same item is available on Bestbuy for $50 it's obviously not a good deal for consumers, but also wouldn't you want them to "suppress" that listing? Now scale that across millions of products--there's no longer people making decisions, it's just algorithms looking for signals. Is there a better or more objective criterion they can use than "this is for sale elsewhere for a lower price"?