CNN first broadcast on June 1, 1980. Fox News Channel didn't exist until October 7, 1996. Many of the most pervasive problems with all cable news started with CNN. It's hard to fill 24 hours with pure news, so opinion got added to the mix, such that now primetime is all about the opinion. As a sibling comment stated, Fox just beat them at their own game in that sense.

It seems like public discourse is by and large worse off due to the way news media is structured. In the drive for viewers and ratings, the media has become extremely polarizing. People make it a badge of pride that they don't watch X or Y network. You expose that a bit as well when you assume that the words I wrote should only apply to Fox. All cable news media is problematic in this day and age.

CNN and 24hr cable news has not been good for journalism. Opinion pundits responding to events before the facts can even be collected along with daily shows interweaving narratives pre-dates Fox News. Fox News played their game more blatantly ruthless than the others and beat them at their own game.

I think your statement says more about what you are prepared to believe, than about any notion of absolute truth. MSNBC is often a mirror of Fox in equally (un)believable proportion.

When I was young, I got into short-wave listening. This was during the Viet Nam war. I used to listen to the English language news from Radio Moscow, then the news from Voice of America, just for the sheer, rollicking entertainment value of the ideological whiplash. I suggest a similar exercise using modern context -- it will sharpen your BS detector.