I don't think the physical object is really relevant. Imagine we all had robotic painters in our garages, which given $1 of materials, could precisely replicate

I don't think the physical object is really relevant. Imagine we all had robotic painters in our garages, which given $1 of materials, could precisely replicate any brushwork from some images. Surely that wouldn't destroy the value of famous originals? Because their value is based on provenance, not the physical difficulty of (re)creation. NFTs are the same - replicating a JPEG is trivial, but the replica won't have the same provenance.