HQ, the only thing you have added to this discussion is that buyers cannot leave feedback if they have not paid.

In this you are ABSOLUTELY wrong.

I currently have four items in my buying account that I haven't paid for yet.  ALL have the option to Leave Feedback.

I have also left feedback, including neg, for items I haven't paid for, for example when the seller cancelled the transaction because the item wasn't actually available, or any reason I chose not to pay that seller. They are still there in my Feedback Left for Others to this day.

Check your Purchase History page next time before you pay for them, there's a drop-down menu under where it say Pay Now.

The only time a buyer can't leave fb is if an AUTOMATED UPI case is opened (ie the seller has the automatic settings switched on) which prevents the buyer leaving feedback.  If the seller does it manually, that door is still wide open until the case is closed by the seller and the buyer gets a strike.  This has been rehashed over and over on these boards.

Also, I still stand by the statement that defects do not happen for cancelled transactions Buyer changed mind - unless I have a magic account or something.