I think you might find some answers in Walter Benjamin's text, "Art in the Age of Mechanical Reproduction".
Benjamin's Romantic theory of immanent criticism insists that the work must contain its own inner criterion, which separates it from the author and the conditions that surround it.
It's not a long read and it centres around examining the quality of art.
John Berger also talks about this across a few different books.
The short answer feels essentially mimetic, that the idea of the art travels further than the image and as such has an aura of authenticity that can transend industrial reproduction and commerce.