But if there is a one-to-many pattern of information sharing (e.g. an organized attempt to share content) to unrelated parties, then that content should be vetted for veracity. Either FB does it, or they surface it for others to flag it.
This is extremely toxic for freedom of speech and information sharing and is a veiled gateway to censorship. It subjects veracity to the approval of an unknown group with unknown motives than you're assuming are righteous.
There are notably verifiable "fake news" stories that we can all logically assume are fake, but the matter of veracity is ultimately defined in opinion. Even if that opinion is your opinion on what news source to trust.
The only people that can truly verify information are those that are present when it's generated and we rely on those people to be truthful. You trust your source of news when you determine something is fact. Bob's Blog reporting "Obama sends troops to Texas to ensure 3rd term" will receive a notably different reception than NPR reporting the same thing. But ultimately that difference in perception is your opinion of what constitutes valid information. Unless you're in Texas, do you really know for sure?
If an article is 90% correct, but 10% unknown or possibly speculative, who makes the call on the validity of the news and story? What if that 10% of the information dramatically affects the context of the other 90%?
If a police investigation determines that a police officer lawfully killed someone in the line of duty, but someone disputes that with another story, who do we trust? Should one of the stories be suppressed because it can't be validated? Personally, I prefer to reserve the decision for what I consider valid for myself, not the overlords of the platform I use to consume the content.
Progress cannot happen in society without good & bad ideas freely propagating, and individual decisions to buy into them or not. Every significant cultural movement stems from a counter-cultural uprising, and these sorts of things would be swept up in the "vetting".
Again, it's 4chan with more rules. Anybody can post anything. It's not a place of fact or truth. It's of people sharing their lives, thoughts, hobbies, opinions, notices, likes & dislikes, etc. Some extremist $SIDE-wing Facebook channel is simply posting such things. It's not an official channel for trustworthy news, it's users being social, whether that user is Aunt Flo or CNN.
The core problem is that people think it's a "trustworthy" information platform (and Zuckerberg wants that trust for more customer buy-in). It's not. And it won't be, unless you remove the core personal family & friends social aspect of it.