It all comes down to technology. If we had the technology to create an atom-by-atom replica of a painting, then this justification would need to change. People

It all comes down to technology. If we had the technology to create an atom-by-atom replica of a painting, then this justification would need to change. People would probably say “but these atoms are still the original ones.” Of course the only way to verify that at this point would be to have evidence of a chain of custody, which would likely be very difficult to establish with any confidence. So paintings just “lucked out” and already had a convenient scarce item that interested parties could agree represents the “original act of creation of the work of art,” because the technology to create an exact copy doesn’t exist, and it’s extremely expensive and difficult to create a convincing forgery.