just got back to playing after a long gap, came back for the multihub, but I see the same problems. Since airport size is 100-0, why not just fix a max number a player can base in, instead of the not in top ten rule. Lets say 360 instead of the 6 airport limit , so you could base in 6 Memphis size airports or two ATL and 1 memphis, your choice.
By the way, are 19 pax planes below 500miles radius operations profitable? I mean can you survive, or is the 30-40 seat limit still the lowest you can go without getting ridiculous staff numbers per plane?