there’s no value in the copy of the painting, irrespective of the duplicate’s quality.
Only if the copy is a digital image. If it’s a physical copy, it has some value, precisely depending on the quality - and scarcity - of the physical object. Granted, the original will always have more value (unless you manage to pass off a sufficiently-good copy as the original), but that’s because Guernica didn’t start off as a digital image - there’s only one of it. And this has always been the problem for artists working natively with digital images - value is in scarcity, and if there are potentially an infinite number of identical copies, the value of the work is zero, from the traditional capitalist collector/speculator point of view. (There are, of course, other ways of funding artists, but there’s not a lot of money in them, relatively.)
Some natively-digital artists have been hoping that NFTs could be used to create scarcity in digital images (and therefore value), but on a fundamental level they don’t actually do that, so all the hopes built on the back on them are based on misconceptions and doomed to disappoint.
No, not at all, the issue is claiming that they’re “exactly like traditional paintings” when they’re absolutely not - their nature and dynamics are completely different. There’s certainly similarities and parallels between speculation in NFTs and art world speculation in paintings (at the moment, anyways), but the things themselves aren’t comparable. Pretending they’re the same is why the NFT market is a house of cards built on sand - as soon as the market fully comes to the realization that NFTs themselves don’t even address the issue of digital scarcity, the whole thing collapses.
Yeah, this is one of the major problems with NFTs - they have nothing to do with provenance (which must be shown in a fully external process), nor (as shown by the case of Seth Green’s monkey pic) are they necessarily even accurate records of financial transactions, so the blockchain entries don’t even prove ownership. The NFT itself does… nothing.
I’d argue that with these big art institution sales of NFTs, the art institutions were the ones giving legitimacy to the NFTs, rather than the NFTs legitimizing the digital images being sold. The art institutions could have said “here’s a jpeg and an actual physical receipt for it” and it would have worked entirely the same (and probably been more valuable in the long run).