I agree that many probably most buyers do not Search by category, and probably never notice if their find is in the wrong category, whether because of carelessness or fraud on the part of the seller.
Ebay said that the seller closed the account
More likely the account was closed by eBay, since member accounts take nearly six months to be fully closed, in part because of financial obligations like this.
Were you talking to a phone rep?
They are notorious for bad advice.
Try the social media chats.
https://www.facebook.com/eBayForBusiness/ — Message button in upper right on landing page.
https://twitter.com/askebay?lang=en
https://community.ebay.com/t5/Selling/How-do-I-contact-Customer-Support/m-p/32016431#M1783851 -> Automated Assistant, type AGENT -> enter. You will then get more options.
The social media Chat accounts are covered by trained eBay employees with some authority.
And you get a transcript so you can compare what you heard with what you were told.
I'm a little surprised that MasterCard has such limited chargeback coverage.
Did you recieve anything? Was the watch you were sent counterfeit?