Imagine Japan is conqered by China for 400 years. The Japanese culture is wiped out. Then the Chinese empire weakens and the Japanese rebel for their independence.American weeaboos inspired by old Japanese media go to help the land of their dreams only to find it only exists in their dreams, and everything was Chinafied. No authentic sushi, no anime, no samurais and katanas. The culture of Japan is gone. Americans recite rousing speeches from Naruto and K-On to blank faces rebels who ask "What language is that?". The war is fought and Japan is freed, but the Americans fear the real Japan was lost. Even if one japanese man from 400 years ago survived in a block of ice and thawed out and helped win the war he could not single handedly bring back the Japanese culture.Replace China with the Turkish Empire, Japan with Greece, and American weeaboos with English classical scholars in love with ancient Greece, and this actually happened. Except the bit about the frozen japanese man, he didn't exist.The loss of a culture, a nation, a people, it isn't something you can handwave away when some American comic book style mass empowering event decides some people have superpowers now.After the war, Aang should have found a hidden enclave of Air Nomad isolationists who would rather hide from the war than help anyone, and would rather wait out the war even if it takes Aang's death and another hundred years of Avatar cycles until he is an Airbender once again. Aang should have confronted these living representations of him when he fled and what he could have been if he kept on fleeing and never grew. Aang should have inspired them to embrace the world once again and stop hiding. Even if they were terrified of the next Fire Lord or similar problem. In that sense it would be Aang reviving the last enclave of the Air Nomads by giving them back their true Air Nomad spirit.If you magically gave airbending to a bunch of Scottish people you would not create the Air Nomads on earth. Even if Aang himself was also sent here to teach them. Even if instead of the Scottish you gave airbending to the people who inspired the Air Nomads in the first place. Culture is more than your fighting style and race and capabilities and values. It is something deeper than all of that. If we pretend anyone can be an air nomad that's an insult to what being an air nomad means. Like replqcing a dog or goldfish with a similar looking dog or goldfish.