DG wrote ...That is, rather than the "you can't make me" approach, but the "why do you think you can?" approach....

The 'why do you think you can?' approach appears to be covered in Other Terms point 1. 

• Buyers and sellers permit us to make final decisions about all cases, including appeals.

   

  Which obviously means all sellers who continue to list on eBay have agreed to that T&C - not only not a level playing field, but full of rocks and unseen deep holes where sellers can take a spill.