This whole endeavor was fairly ill-starred from the beginning. Looking at their list of arbiters, they're pulling in places like Politifact whose bread-and-butt

This whole endeavor was fairly ill-starred from the beginning. Looking at their list of arbiters, they're pulling in places like Politifact whose bread-and-butter is in parsing out politicians' statements themselves and ranking them N pinocchios, or whatever. This kind of "fact-checking" is inherently political, since everything depends on exactly how much charity you grant the speaker for simplifications that may or may not convey an accurate picture of reality, or out-of-context presentations of true facts that don't have the implications a naive audience might draw. Therefore, all such attempts will have a necessary and massive credibility problem; it's very easy for non-mainstream elements to simply paint the fact-checker as biased. See, for instance, the alacrity with which Trump and his supporters turned around the label "fake news" itself as an insult against the mainstream organizations they feud with. Meanwhile, there's the separate issue of clickbaity news stories that describe events which simply never happened, presumably for the ad revenue. Unlike political stories, these can generally be quickly and objectively categorized as such; however, Facebook also has the incentive to keep these on their platform to drive more engagement with Facebook, and so it's near-certain they won't be productively addressed, despite being a problem that everyone can agree on.