I can’t imagine any sort of verification system not being completely overrun by bots/people on fiver/ mechanical turk immediately unless you tied it to meatspace IDs in an know your customer sort of way, in which case you would definitely need a central organization to do said verification, which eliminates any possible need for a blockchain as said organization can just use a faster, far cheaper, and most importantly for this application editable database.
More to the point, no one doubts that an article published by one organization was secretly published by another, but rather that they secretly used AI in the writing process, which also negates the system because that organization is never going to tell you which articles are done by AI, and any sort of reporting system for the entire organization or a specific author is just going to be immediately and constantly used to review bomb.