I do remember when Metallica headlined, and everyone treated it as a Big Thing. There was a stupid guardian hot take about how they don't belong there, and the babies in mogwai did their tedious "bunch a SHITE" thing, and Metallica said something during their performance like "well, what do you think? Does heavy music belong at Glastonbury?!"
Yeah, it was treated as a Big Deal, like it was progress of some kind, a major revolutionary step forwards, and I just remember thinking: guys! You're one of the biggest and most privileged bands in the world! You're not the underdogs here! You don't need this!