Also doesn't allow other to update metadata or even submit for review. Wikidata has a property for Internet Archive ID, so it wouldn't be conceptually hard to

Also doesn't allow other to update metadata or even submit for review. Wikidata has a property for Internet Archive ID, so it wouldn't be conceptually hard to construct a parallel metadata store there, but it would involve hundreds of millions of triples so it's definitely "hard" in other senses.