My main rebuttal is largely that Amazon has been going to shit, oddly.
They claim that search is getting worse on Amazon. And that the old "organic search results" are worse now. I agree it is getting worse. I disagree that it was ever good. Largely the problem is one of volume there.
They have claims that some algorithms push sellers down. I actually am interested in seeing that explored more. My gut is that it is just poor execution from Amazon. Not from incompetence or malice, mind; but it is a stupid hard problem that nobody is executing on well.
My "excuse" of the favored vendor clauses existing is, I confess, largely sour grapes that that is allowed at all. It really screwed over a lot of small companies that tried to partner with Walmart back in the day. If that goes away, I'll be delighted.
But the entire study of the buy box is questionable. Amazon has long done everything they can to get it to "1-click" so that you buy. They famously had a patent on that nonsense. Yes, it makes a big difference on purchases and such. No, it probably is not being "weaponized" against some sellers. The entire dream of Amazon there is to get a sale from a web view. They have almost certainly tried all they can to take whatever step they can to increase that. As such, it is a very volatile place to be located and it will take effort to keep a vendor there. Pretty much period.
Can they show that losing a preferred location will lead to reduced sales for a vendor? I'd be shocked if they couldn't. The question there is why did Amazon do it? If they did it as retaliation to a vendor, that is BS and they deserve to get fined. If it was just them doing what they can to convert more sales? I'm less clear what to do there. If we want better rules around that sort of thing, I'm all for that.
I don't actually know that I can stay on this discussion much more. You haven't really offered anything other than "I disagree." And, that is perfectly fine. I am hoping to see some points that strengthen the case, though.