On our selling id, which runs auctions,  we've seen an increase in scammers, non payers and general timewasters this year. When we investigate these, we invariably find that the bidder is already on our blocked list under one or more different id's.  So they've just used a different account to bid.

This costs everyone time and money, us when we fail to spot one and get scammed, and eBay because they lose fees, and we invariably have to move the item to a different platform once its been targetted.

Obviously I would prefer it if eBay policed the site better and dealt with these users, but thats a forlorn hope. What could be done, is if a user was on a sellers blocked list, then all the users linked accounts should also be automatically prevented from buying. That is something which could be implemented fairly easily, I'd have thought.