My 2 bob's worth..   Feedback should be given for both Buyers and Sellers. Not just Postage <- I h8 that 1   Sellers could have a mechanism to detect NPB's and reject their bid if their rating indicates such practices ... Some fine tuning and eBay could become attractive for sellers, who are constantly being charged for such.

Sellers DO have a mechanism for detecting NPBs. It's called blocking those with a selected number of strikes, starting from two. No need to reject their bid (and the issues attendant thereto); they don't get to bid in the first place.