Sorry to be a dick but this is only 50% true. Whilst I agree that social media has an AWFUL lot to do with this - its why I personally dont use social media at all, I think its a cesspit, its a tactic that fox news has been using for a couple of decades. One of my slightly sad passtimes is a passion for American politics for the past 30 years and what fox news would do is create a headline from something innocuous, then they would get one of their morning shows to run a segment which in turn would be picked up by a later edition of a news programme on fox and so on and on until its been brought into the national consciousness. Its very clever and creates its own headlines depending what Murdoch ( or Ailes at the time) wants their agenda to be. Thats the first I know of of creating an echo chamber but I do totally agree with you, social media just ramps it up into overdrive to reach out to many more people.
Okay, Im done.