They promoted the experience of seeing a non-WWE show with a 10,000 person crowd which became the draw, sure. They did not promote themselves as these big box office attractions, it was always the concept that drew attention. And then all the talent wanted in once they saw it trending so much. It was just as much a show promoted by the internet fanbase as it was promoted by Cody. They certainly were not his fanbase before this started.
AEW is the same thing. It will never be about Cody or the Bucks. It will always be about being a mainstream alternative to WWE. And they will succeed, not because people enjoy the Bucks or Cody, but because fans want a mainstream alternative to WWE.