I believe you are mistaken. 40 years ago, there was no alternate media to destroy or expose them. At least not any media of consequence.
Consider the media coup that was Watergate.
We have been living in a mediacracy for at least 50 years.
The WaPo, NYTs, and 60 minutes did numerous false exposes and articles in that time period.
Well over a hundred years. The media became liberal when it fell in love with Russia's Red Revolution and then communism, the workers paradise.
It had to start deceiving it's audience and then itself when it became obvious that communism success was a lie and it would never work in the real world.
The left media has contorted, distorted reported, and outright lied to protect the fallacy that communism/socialism has/can/will ever work.
It just sounds so good and it makes you feel so nice to 'he'p' every poor, down trodden slob in the world {using someone else's money}.
Free everything, it's wonderful.
Make the rich pay 'their fair share'. Hoorah.
The media is the deep state.