I agree with the original quotation, but I may be reading it differently than you are. Obviously, the artist only "sees" what the artist sees. They don't control others, and others "see" myriad things in art (and literature) that may or may not have been intended by the artist. I used to dislike modern art intensely. Much of it seems like fraud, to me (e.g., Marcel DuChamp's "Fountain," or Jo Bair's "Brilliant Yellow #__") It's not fraud; it makes us all "see" something different. Makes us think.

An old friend, the artist Arturo Herrera, did a video series talking about this, and it finally clicked for me. This isn't about seeing literal representation of the subject of the artwork. Art is evocative, and each of us brings to it the sum of our experiences. Therefore, what the artist does is to strike a chord within us that touches on all of that. That's why it's art and not merely a photograph.

I don't think Degas was so much passing judgment on what was art as making the observation that art is different things to different people. Art is where the artist loses control of the work, and the audience imbues it with meaning.