It failed because an "immutable cryptographic proof" that the information being represented is valid is about as useful as a handwritten certificate that says you own Sagittarius.

Cryptography cannot verify your ownership of Sagittarius; it is not an authority. It cannot prevent you from claiming you do, either: anybody can enter whatever they want into the system.

And funny enough, this cryptographic lock and key isn't even undisputable. If you have a dated record from 2020, and someone else wants it, they can just verify theirs on a different chain. Who is to say which chain is "more correct"? The dates? Dates don't matter. If you were unlucky enough not to publish your work before someone else does, you don't cryptographically own your work. If you were lucky and you had published, someone else can just lie that they weren't ready and you stole it from them. So, even with all of our fancy math, we're still back to he-said, she-said.

Worse, most blockchain records I know of are way too small for images, let alone video, so all they do is cryptographically "verify" URLs to the work. What exactly is the point of this? Can the files served by these URLs not simply be... changed?

I know they can be changed because C2PA has this very same, exact problem.

The blockchain is, at best, a database. The fact that it's public doesn't mean anything---it might be worse, even.

Why bother reinventing all of this? We have institutions already that keep records. What social good is bought from having the most public of all records?