Very sad to see.
Recently, some kids made a massive set up in some sandstone overhangs in a Reserve that I used to play under as a child. Previously, they had seen no damage, all done in a one off event. Graffiti, milk crate sofa, illegal fire etc.
The overhangs are much nicer than this photo lets on, it was taken to show the most damage, not to highlight the rocks. Bouddi is still far, far superior of course.
I promptly removed the milk crate furnature. It must have taken half a dozen people to carry them so far into the bush. I've still been meaning to clean off the graffiti myself, even if it does damage the rock faces slightly, it'd still be an improvement to the low-effort graffiti.
I find this sort of graffiti quite cowardly. Graffiti has it's place as urban art, a way for people to criticise society by damaging societies idols (statues, advertising billboards etc.). I remember fondly the time someone graffiti'd "CONSUME" over those annoying video billboards at Chatswood station. Graffiti in a national park is the complete opposite of this, there's zero risk and your art is sending basically zero message. It's like a toddler drawing on the bedroom walls.