It could just as easily be a function of population growth, easier access (e.g. more info available about how to get outdoors), better marketing by the NPS to attract more visitors, etc. More people visited the parks last year than ever before.
Sure it's anecdotal ... but you did ask.
(That's probably a good thing; I'd have preferred it if they'd had to place some signs as a restorative justice gesture).
I would expect most of the mining company executives organizing whole mountaintop removal are well over 25, since most executives are over that age. Goes a little beyond graffiti.