The age of arena rock has past. Get with the program the festival is where most up and coming bands play.I'm just drawing a comparison that bands that I mentioned and of that era. i.e., have a couple albums, and suddenly selling out sports arenas. That was very common in the 80s. But all but died, it seems, in the early 2000s.
Now the rocket ship a band needs to be on to achieve that seems bigger. Coldplay became enormous is just 3 years. Oasis exploded pretty big...late 90s. But I struggle to think of a non-pop-machine artist that did this recently.