I only know a bit about it, but when we were young basically can happen because livenation gave pretty significant advances to a lot of bands who were struggling in 2020-2021 in exchange for a guarantee that the band will play their festivals. As a band back then, a $50k or whatever advance was kinda impossible to turn down. So livenation essentially bought fealty from every emo band and can now host a festival with all of the bands people my age liked in high school.

It is one facet of the disgusting wholesale capture of live music by livenation/ticketmaster. Many venues are also now exclusively run by livenation for the same reason - livenation "rescued" them during the pandemic, but now are reaping massive benefits on what were pretty cheap investments, at a time where there was plenty of cash flowing around for the investors and the venue owners and local promoters were fucked.