Social media, and all of the "talking heads" on network news and talk radio, are basically in an arms race, just like advertisers have been for years. For instance, Coke can't stop advertising because then Pepsi or another brand will take over, i.e., they have to keep it up. We are now at that same point with politics: everyone has to keep it up, and even more so; constantly upping the ante. Facebook is the dominant platform for upping the ante, which gives them money, and more importantly, power.