The “facilities” are a main reason I rarely go to big outdoor events. My teenagers have been to some one-day multi-performer concerts, such as the “Warped Tour.”
I think that, as with any type of recreational activity, a point will be reached where the supply exceeds the demand, and then some will go out of business.
One-day events are as far as I’ll go. After 10 hours of walking around out in the sun (if you’re lucky), I need my own bed to sleep in :)