Korn are an interesting one, on the surface they shouldn't be headlining. However, the crowds they pull at Download are massive, and that alone might be the factor for them to get their chance
Agreed, but there is a correlation between experience and performance skills (which is not the case with chart hits).
Olivia, Dua.. they sell. They're on top of their game. But it doesn't say anything about them ad performers. Don't know about Olivia, but Dua is even a classic meme. Saw her glasto set. She can't perform for the life of her.
And while their 2018 set was a mess, I think that AMs 23 set was legendary.