> You can eliminate those problems entirely with a blockchain and smart contract that requires identity and proof of such.
You don't think if the problem were that easy to solve, it would be solved already? Throwing blockchain in the mix gets Facebook nothing that it couldn't get today by just partnering with organizations can verify identities.
Not to mention, the "fake news" issue isn't largely an identity issue — there are plenty of people and organizations willing to lie on their real accounts to further their sociopolitical agenda, and plenty more people who don't care if something's true so long as it confirms their existing viewpoints.