it's absolutely stupid
because it rules out all flights, even regional connecting ones...Say you want to do an itin like BOG-OPO...You've got no way of crossing the pond before connecting and you have to go via the USA (hassle)...You manage to find a flight from BOG to the US and another one to somewhere in Europe.... but AZ and OK don't fly to OPO, so the best you can hope is an AZ to LIS...If you do manage to find availability on this, too, you will have connected 3 times and still need another flight or a few hours on the train before reaching your destination. that's instead of a simple CDG connection.
How convenient.