Your take is easy cynicism and you appear to have ignored the entire point of the article. Right off the bat the author says it isn't about criticizing the pain

Your take is easy cynicism and you appear to have ignored the entire point of the article. Right off the bat the author says it isn't about criticizing the painters -- it is to show how even though some shadows are terribly wrong, they don't stand out as jarring to casual observers, and gives some insight into how our brains interpret images. If errors of this magnitude were made in other aspects, say in face symmetry, the spacing of the eyes, etc, the resulting images would be not just uncanny valley territory but would look terrible.