An interesting argument... which could be extended to "why paint from life?" because you're just copying what you see.
In fact, some artists who paint completely from their imagination or who create nonrepresentational art have this exact objection to just painting what you see (even without photographic reference), which they don't find interesting because it's not creative enough for them.
That would be 3D but still effectively painting from a "photo".
It'd also be incredibly difficult and straining for your eyes of focussing on a canvas and then on an AR image
Since I'm a photographer, I guess I didn't get why he would need to copy a photo exactly.