> Graffiti, fundamentally, is a defacement of public property

Both wrong. Neither is defacement the point nor doing it to public property. Fundamentally it's a visual art form and whether that's on private or public property is insubstantial.

It's surely intervoven with anarchic protest and that's where the defacement angle comes in. Similarly, public property as a symbol of the state that is rejected plays often a role. Though that's ironic too since if the "artist" comes from a left-leaning anarchic background then damaging public goods is kinda counterproductive, as opposed to private property of the rich who are the more usual target for symbolizing oppression of the poor.

"Can you tell the jury what you told investigators when you decided to use computerized directed energy weapons to target civllian infrastructure?"

"...rule of cool?"

You’ll probably burn your retinas with the backscatter

Defacement is not the point of graffiti. It's fundamentally visual, not fundamentally destructive.