The problem with all the upgrade selling is that when the instruments don't clear, there is no reason for anyone to fly UA past the status they aspire to. So in my case, it may end up costing UA the incremental $13k in flying that I can now plough into AA to reach EXP.
UA will never know what it is missing because they can't see the revenue they lose unless I am sending them receipts for AA bookings...which is far too cumbersome.
I can't be the only one who thinks that way. Question is...do others do the same if they are primarily AA or DL fliers at such a scale that it all cancels each other out.