The reason our democracy was stable in the era of mass media (1920-1995) was that the private companies felt an obligation to keep discourse within certain bounds, partially for civic reasons, and partially for fear of regulatory consequences.
This also prevented independent points of view (e.g. LGBT) from having a voice.
This started to break down in the '80s with the rise of right wing talk radio, made possible by Reagan's deregulation and the elimination of the "equal time rule"
(Which also allowed Fox News to exist)
If you had fringe ideas, like the John Birch society, you were not going to get distribution on CBS News with Cronkite. But you were free to run your own newsletter, conferences, etc. Freedom of speech, not freedom of distribution. Since distribution was a public good.