I think in general Facebook has a bias towards inflammatory posts - and other platforms for that matter as well including HN actually. Also it's easy to blame the village idiot for everything, but I don't think Donald Trump or Alex Jones are village idiots. They are surely idiots but left the village quite some time ago and gained popularity before Facebook (InfoWars was founded 1999) - although FB surely was an accelerator stage.
That said, the village idiot is harmless and I think aristocracy (rule of the elite) is definitely not the solution. But what is true that the normal filters in an offline community haven't been translated online yet.