The problem in this election was that Facebook did exactly what it was designed to do: show people more of what they wanted to see. Unfortunately that creates extreme echo chambers, where blatantly false news ricochets around the site, blindly liked by partisans on each side.
So that leaves open the question of what to do.
On the one hand, Facebook is a massive media company, and I am not comfortable handing them carte blanche to police and control the speech of their users. On the other, Facebook's current policy of "neutrality" creates an environment that favors political isolation and the spread of outright falsehoods.
At the very least, it seems Facebook could do something about purveyors of those falsehoods algorithmically. But even then I have my misgivings about a private corporation, or really anyone, determining the acceptable range of public discourse.