I think there's a point of diminishing returns on listing every band, on a poster for a big festival with a bazillion bands.
If I were the promoter, and I'm not, but if I were, I would have asked for the poster to list just the marquee acts. If this is the alternative.
I'm quite certain that this was NOT the designer's call, and that they were doing what they were asked to do.
But yeah...cereal box, with the ingredients on the front. Slight prominence to headliners Wheat Flour, Corn Syrup, and Vegetable Oil.