I don't think it's blackmail. I wonder if brands like Wüsthof got exclusive agreements as part of selling on Amazon so that nobody else is allowed to list their

I don't think it's blackmail. I wonder if brands like Wüsthof got exclusive agreements as part of selling on Amazon so that nobody else is allowed to list their product, therefore eliminating the knockoffs. But without an official listing then Amazon would have to sort through every reseller to see if they are selling legitimate products or not, and what incentive would Amazon have to do that?