Ebay has always had access to your "back up" account. In fact they could freeze your personal account if they suspected fraud both to protect you and the buyer. It is the key difference between between Paypal and a traditional credit card processing account.
Read the fine print.
As to the new agreement: before it reaches the point where they transfer funds to a complaining buyer, you have plenty of notice and time to respond. I have had two cases where packages went astray (God bless the US post office). Once I was the seller; once the buyer. In both cases we settled the problem amicably and Ebay never got involved other than to notify us that there was a dispute.
The rule is to protect buyers from scam sellers. A buyer can protect himself by buying only through Paypal. Check or credit card can leave them holding the bag.
That said, I have never been scammed on Ebay nor do I know anyone who was. I do know someone whose account was frozen because he tried to transfer funds from a friend's computer. Paypal red flagged the transfer and he was notified. Meantime, his checking account was frozen (or so he said) This is not someone I would trust so I don't believe that that was exactly what triggered the freeze.
Donuel, I don't understand your comment.This is an extra protection for buyers.