Whatever the solution is for misinformation, if there is one, I am quite certain that it will not be invented by Facebook.
Facebook (or YouTube, or Twitter, or whoever) can try to come up with even more infoboxes or disclaimers, but it will continue to exist as long as it is given a platform.
The original sin of social media comes down to the idea that anyone can post, and that virality begets virality. Shocking content is presented on the same level as traditional media -- and in many cases, can exceed those traditional news sources' reach.
FWIW, and disclosure -- we're building a platform that aims to combat misinfo by making it only for news. (https://blog.nillium.com/were-not-an-aggregator/).
Our reporters follow an Editorial Policy, that comes with consequences if they break the guidelines. Virtually every respectable news org has something like this -- we're just making ours public. https://www.forthapp.com/docs/policy.html
Until we hold the reporting produced by professional reporters -- reviewed by editors, fact checked, and held in check by an editorial process -- at a higher esteem than what Firstname Bunchanumbers says, misinformation will continue.
Having worked in a news organization, I wish I had more faith in this statement. Most reporters are woefully out of touch or depth when covering complex topics. As a finance major, I'm often surprised how often the explanations for basic topics are wrong or presented without any nuance.
That implies all ideas are given equal visibility, but we already know that social networks prioritize content that's outrageous or controversial over content that isn't.
You want a free exchange of ideas? Start by fixing the algorithms.
There is real enduring value in being a source for information that is true and trusted. It is possible that Facebook might choose that path.
The harder question is understanding what is true. "Galileo's head was on the block; the crime was looking up the truth."