I don't think the problem is that "citizen news" are not fact checked, because generally, citizens don't create fake news, and when something is worth reporting, there are multiple distinct reports.

Fake news are created by news spammers and propaganda organizations. These guys do it on purpose, for cynical reasons. They won't stop, so we need to filter them out.

What is needed is a blacklist and a way to collaborate in fact-checking. I often seek Wikipedia for news for this reason - it tends to be more fact checked and complete.

After a news piece has been tested and found fake, then we need to apply machine learning to quickly identify all clones of that news floating around (this is easier that the original problem of detecting if they are fake).

So basically the internet needs an immune system.