Back when going multimedia was very primitive and was clearly just a shiny feature with no direct benefit to anyone other than for the creators to partake in new world, I'd have agreed with your statement. In the current situation of muted Facebook videos being a major form of (dis)information distribution, everyone can point to all-encompassing multimedia communication as a potentially extremely lucrative medium. Therefore there shouldn't be any surprise as to the prevalence of that type of content.
This leads to some perverse incentives, though...I have started to see like-farming "tag your friends" pages will post a video of a static image, overlaid with a subtle movement effect like falling snow, undoubtedly because someone realized they'll get more eyeballs from the all-knowing News Feed algorithm if their content is video.
