This quote argues that the more photographic a work of art is, the less valuable it also becomes. It is also considered less powerful and creative.
What this quote most likely wants to convey is the idea that art is not meant to copy reality accurately. Instead, art is meant to be creative, innovative and emotional. It should interpret and manipulate reality, as opposed to copying it. A work of art that simply imitates reality is one that is not particularly creative.
