Your complaints about this system are legitimate, but I think you’re mis-attributing them to blockchain. When you cross from the physical to the digital world, blockchain still works, but only if you keep humans involved to validate the data entry. In the case of the art, that would require physical inspection and possibly tagging the piece. I’m imagining an RFID tag embedded in the frame or similar. Once that piece is done, then this becomes a useful piece of tech for managing provenance because of the transparency it allows.
The general supply chain problem is similarly improved. You still need tamper-evident seals on crates. You still need people verifying at the end (at least) that what is stated in the blockchain manifest is actually there, but you can do it with less human interaction and less verification and more transparency.
Thats where this, and the general supply chain problem, get helped by blockchain. The current paper systems used in global commerce allow for many opportunities for fraud because of the many many manual, paper-based steps they involve. Those get driven out as distributed systems shine lights on bad actors. Once a problem is discovered and someone asks “Who caused this?”, the immediate answer isn’t “I don’t know, it will take me a few weeks to go through the paperwork.”. The answer is “We got this thing from Joe at XYZ place, let’s go talk to him.”. Therein lies the value.
Blockchain can’t solve for garbage-in/garbage-out, we still need other controls for that. That’s not the problem it’s trying to solve though. Look at the work Maersk is doing for example of how applying blockchain well can be helpful. Ibrahim Gokcen talks about it here: https://events.technologyreview.com/video/?event=business-of-blockchain&year=2018
Lots of good talks there, but that and Frank Yiannas’ talks are the most relevant.