This is my thought too that the rate of people who call up AmEx and want an eBay chargeback is causing AmEx to reverse transactions a lot more often than other card issuers, and it is not strictly a merchant fee issue.

I think it is perfectly acceptable for eBay to drop AmEx and perfectly acceptable for consumers to decide to not use the website. It seems Facebook Marketplace is the happening place, but yeah I am not going to find what I really need there. The truth is most of the eBay sellers are really big and have access to items and inventory that I can't find cheaply locally or elsewhere. And most of these sellers cross-sell on Amazon or Walmart anyway, so...

As a result, I can't see eBay finding a way to settle this with AmEx. Of course, it wasn't that long ago I was redeeming AmEx Offers for eBay.