I think the premise is reasonable that FB (and other gigantic social networks) might be hurting democracy to some extent, but I also agree that the extent described here is absurd. However, perhaps ironically, I think the commonly held opinion you're expressing is actually dangerous. It's bad that people "blame" things too freely for their team's loss in democratic elections, but it's unavoidable, and while I do think there's more of it this time around, I think it's only because of a combination of two things: 1. There's more stuff to blame this time (right or wrong). 2. The winning team had a more mocking and disrespectful tone this time, openly represented even by the winning candidate himself, which is highly unusual.

My point is that your list isn't mutually exclusive (Facebook, interference, racism, bad Democratic candidate), and, anecdotally, every human being I know in person agrees those are all real issues that contributed, and only disagree on degrees, and those disagreements have always been reasonable. What I think is dangerous is broadly dismissing all those issues under the umbrella of "you lost, deal with it." Irrational blame-seekers will always point to every single issue they can - please don't let that cast a shadow on the issues themselves if you can.