Isn't pushing propaganda what mass media do all the time? So are we looking at the pot (the "old school" mass media) calling the kettle (facebook&co) black? Paladins of freedom (if you ignore the obvious conflict of interest) and democracy (if their ideas are your ideas or somewhat similar), indeed.

At least Facebook, differently from "old school" mass media (granting for the sake of the argument that facebook is a mass media "entity") had no actual intent to push propaganda. It sold ads. To the wrong people? Maybe (granting for the sake of the argument that its selling ads to those people moved votes).

Democracy has been decaying from the start. It's decaying even faster now, but people putting the blame on facebook and the crazy guy that got elected president in the last round make me laugh. Sorry. :)