Facebook have been censoring what content users see for several years now, it was never a secret but they are quite blatant about it now. But if we remember that Facebook, like Google was set up with American government money via In Q Tel (another open secret).
I was involved in digital communications from the early days, long enough to know that the creation of a communications medium that made mass surveillance and control of information was always part of the plan. More recently we learned that Google are actively involved with US security agencies in filtering certain topics out of search results.
The story about Tim Berners Lee one day saying “Hey, why don’t we join all the computers in the world together so anyone can access all the information in the world,” is just a piece of geek mythology.