The seller in your OP has it set that way BECAUSE eBay allow it. From memory, I think it's an opt-out, too.

I would get good stars from you, presumably, because I DO leave feedback when the buyer pays; we'll never know though. But that is a choice I made and I have no problems with other sellers who, legitimately, feel that the transaction isn't complete until they know the buyer has the item and there are no problems. Which buyer feedback generally indicates.