I am a bit confused here. First this reminded my of the traditional news sites trying to opt out of Google search, but with the very big difference that unlike Google's users never consuming the original site adds or subscriptions, in this case it is still your product sale, just through a new channel.

And yes. I do see how it can be a slippery slope leading to dependence on (paid) Amazon ranking and being roped into their (exploitative) ecosystem.

I can also see how this could cut into franchise or exclusive territory deals, or how this can disrupt your marketing campaigns.

But in the end, is this really different from people selling your products, new or used, on eBay? And would the actions needed to stop this maybe be worse than the actual disease?

I can see both sides. Not sure which eay I lean.