It was the way of all such things, perfectly obvious and you wondered why no one had noticed it brfore.

It in no way detacts from the skills of the artists. For you could see the thrill that David Hockney got from just running his hands over the projected one dimensional image. Caravaggio and company would have been equally thrilled and eager to capture the image in paint.

It was just a way of getting the three dimensional scene onto the canvas. Once there, the painter could work their magic.