You're right, but let’s be honest, most of “spray painting” is just tagging. Even as a kid I found big spray painted murals “cool”, but thought tagged places as “ran down”. I met a guy a few years ago who told stories about spray painting large murals in underpasses, but gave up when others started to tag over his creations.

I obviously don’t have a solution to this, but it’s hard to argue how spray painting is net good even for kids.