the value is in the limited edition asset signed and distributed by an artist. you can verify this by taking the Beeple PNG and re-minting it yourself to see if others value it the same way. or you can take any popular artist's or photographer's signed print like Damien Hirst and create a copy without a signature to see if people value it.
banks and CEX both have nothing to do with the topic of certification of art. neither a bank or CEX upholds the cert.
interesting that you say NFT-as-certs have no impact for notable artists yet there are a variety of notable artists using NFT-as-certs. see: Hirst, Koons, Pace gallery all using NFT. the nice thing is that this tech is available to all, whether you are a notable artist like Hirst or just an illustrator or pixel artist, such as @jmw327.