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.

How does a blockchain make this better than a “simple” 3rd party that you pay to transfer verified ownership of a registered object to another account in their database? They also offer a nice API so you can integrate. Seems much less complicated. For example I can still use my password and if I forgot it I can recover it (even if that may involve some kind of strict check). That is not possible if I somehow screw up my key (as far as I understand blockchains in general).
If (as it appears) the whole blockchain part is behind a web interface, then why blockchain? Wouldn’t a classical (PG, MSSQL, even Mongo) make things easier and faster while retaining the exact same outward functionality?