Facebook's resistance to filtering news on its own is understandable. After all, the creation of Gatekeepers (editors/an editorial staff for media articles) will put them in a new ring - and with their profits driven by Facebook advertising and post-boosting, it doesn't make sense for them to antagonize their paying users.
But the problem of whether or not a gatekeeper system will be abused is a moot point, because Facebook as it is right now is being abused, whether they like to admit it or not. It's easy to say, though, that perhaps news outlets themselves should form up their own vetting committees. But they won't do that, either. And they won't do it for similar reasons as Facebook's.
And so we inch deeper into a post-truth world.