ebooks: Valid use case for blockchain?

I've seen ideas thrown around about X but on the blockchain and they usually are overengineered, buzzword-driven things that could easily be solved with digital signatures in a regular, central database. I've heard of very few examples of problems that really require the blockchain.

Then a few days ago, while on a layover between 2 long flights, a thought popped into my mind: Using the blockchain for validating ebooks.

When it comes to books, I still prefer the paper versions over electronic ones. I don't even own a Kindle. I have bought very few ebooks, and all of them have been technical. And the main reason for this is that I don't trust that system. I clearly remember a debacle with Amazon some years ago when they deleted copies of 1984 from a lot of devices without permission from the users. And it's known that the books you have on these devices can be updated without your consent, which is great for fixing typos but it's got some real potential for Ministry of Truth style revisionist editing. I'd rather have typos any day of the week.

The solution to this, however, is rather simple: Just have a hash of the book handy. Maybe you can calculate it yourself when you download the book, and check it periodically. That way you can be sure it hasn't been edited without your knowledge; but what if it was somehow edited right before you download it?

So, it may be better to have these hashes available online. A simple database where you lookup by ISBN and get a hash, and you can compare it to the one you just calculated. Simple.

But, who's in charge of this database? It needs to be either someone I trust, or someone I don't need to trust. So: Blockchain! A decentralized database with all the hashes of ebooks everywhere. Of course, it needs to be work a bit different from the ones I'm familiar with, which are for cryptocurrencies. My first idea is this: when you get an ebook, you get its hash and then send it along with the ISBN to this blockchain. A lookup will be done first, and if it's there, you get back the hash that's already stored there, and you can see if it maches. Otherwise, your submission is kept in a pool, until you get X number of similar submissions (by ISBN). If the hashes in all these submissions match, then it's added in the next block. If a small number of submissions don't match, they get discarded. If there seems to be no consensus at all (lots of different hashes with no significant majority), then all get discarded, and maybe the ISBN is flagged for good measure.

Now, who makes the blocks? That's always the tricky part. And the problem is, we usually ask the wrong question. Because the answer to "but who makes the blocks?" should always be: anybody. Same goes for "but who can send transactions?" (or, in this specific case, "but who can submit ISBN+hash?")

With any cryptocurrency, you can just download the software and become a node in that blockchain. Same here: anybody should be able to run a node for this blockchain. So the question, then, is: Why would anyone want to run this node? What incentive do they have to do this?

And here's where I ran out of ideas. I don't know the answer to this. Bookstores, maybe... Publishing houses? Even authors might have a vested interest in this. And there's also the detail of how blocks are created. Proof of Work? Proof of Stake? Is there a cost to submitting ISBN+hashes?

I don't know. Maybe I was just too jetlagged and this seemed like a good idea. But it's been 4 days since that, and at least it doesn't sound completely bogus. What do you think?