This post breaks down in so many ways.
Premise in a nutshell: FB allows the spreading of fake news, and this is why HRC lost.
Immediate irrefutable response: Assume FB allows the spreading of fake news. Since they don't enforce any partisan content restrictions (on personal status updates), this makes it equally easy for any political position to spread fake news benefiting their narrative. During this election cycle, I spotted fake news from both sides of the race. So let's start by tossing out the implication that fake news came only from Trump's supporters. Then we can easily toss out the notion that it had any measurable impact on one side's propaganda versus the other's.
Secondary point: Snopes has been accused of operating under a political agenda of its own. The implication that they constitute an example of objectivity introduces a flaw into the chain of logic.
Tertiary point: IMHO a much more honest/impartial discussion might arise from the new proliferation of primary sources online for people to do their own fact-checking. As an example, I went straight to Wikileaks to find out what was there when the story broke. Many acquaintances of mine (from one side of the race) only ingested editorialized, filtered reports about Wikileaks; and many others (from the other side) know almost nothing about the content, dismissing it as the propaganda of a malicious foreign power. In both cases, the stories being ingested are once-removed from the original facts because of an editorializing intermediary. If anything, social media's role in this election served as an agent of confirmation bias - on both sides. Just as partisans choose media outlets that reinforce preconceived notions (CNN, FOX, NYT, etc), social media users accept self-reinforcing memes as fact , and reject those that contradict.