THANK YOU!
I remember seeing Rihanna in 2010 (arguably, already one of the biggest pop stars, and imo by then bigger than Olivia is today). She was still young, inexperienced, and the fact that she's talented and super popular were enough to pull a good show, but that's it. Saw her again 3 years later and there was no point to compare.
Experience is important, that's it.
She played two gigs that sold out in less than 24 hours, so offer < demand. That being said, makes perfect sense and the timings for announcements are not just the festival responsibility.