Trump wouldn't have succeeded without Facebook. Period. He is radical, and his fear-mongering lies don't stand up to scrutiny. Luckily, Facebook is happy to just feed people stuff they are likely to click on, whether it's true or not. The more they click, the more money FB gets. Therefore, it will put stuff that either strongly reinforces held beliefs, or outrages a person with a certain set of beliefs. If you rely on it as your main source of info, you're also in an echo chamber of only like-minded people in most cases among your circle of friends.
AOL fell by the wayside supposedly because it was a walled garden and people wanted the free open spaces of the internet! I wonder if that's true, or if they just didn't figure out how to keep people engaged like Facebook does. For some people, they never ever leave the Facebook website - that's their entire internet experience.