This. The sport is a fascinating microcosm of just how out of balance the world still is, despite all Aang's work (and despite Pema's steady supply of new young airbenders *g*). And absolutely no one sees anything odd about trios instead of quartets; there's clearly no room for an airbender to join a team even if they wanted to. It's really unsettling.

I can see why pro bending would have been encouraged with this particular structure; it's a great way to get people focused on teams instead of nations, so everyone feels like one people. But man. Even beyond dividing the world into bender and non-bender, it is just cementing the notion that airbenders aren't part of the world, really.