Treating Facebook as impartial in this situation is wrong. Its motives may be separate from the Trump campaign, but it absolutely cannot be said that they are impartial, and it certainly cannot be said that they naively allowed their forum to become a Trump echo chamber.
The proof is in reach statistics, and easily intuited from how users complain about Newsfeed being clogged with spam nowadays.
“Liking” a page is no longer enough to get a simple real-time update from that page into Newsfeed for those who liked it. It can easily be buried by the algorithm (which classifies this as “organic” reach). On the other hand, pages that users do not even Like can get 100 times the audience of their “organic” reach, simply by buying advertisement.
Further, Facebook does not bother making much of a distinction between paid advertisement and organic reach material.
It is hard to remember, but once upon a time, “Newsfeed” was entirely separated from advertisement (which was placed in the right-rail position). Newsfeed was once organic only. It was changed to allow for more adverts — and not coincidentally, the page reach statistics for people like Occupy Wall Street went down precipitously, while those of snake-oil salesmen (e.g., “YOU’LL NEVER GUESS HOW THIS FAT CELEBRITY GOT THIN” suggested links) went through the roof — which I suppose this is Facebook’s right, but this has never been adequately explained to end-users.
This is simply not an impartial or neutral way to disseminate news (or other content). It is fair to say that this is analogous to the payola-era of radio — which is an outlawed practice.
To unpack: payola was the practice whereby recording labels paid disc jockeys for a certain number of plays-per-hour for their artists — without any disclosure that the spins were paid for. The fact that certain deejays were, in fact, holders of royalties on the recordings made it even more corrupt.
Now ask yourself, gee, was there anybody at Facebook who might have had some sort of interest in slanting Newsfeed advertisement one way over another?
Oh heavens no, there couldn’t be, right?