They've been pathological liars for generations. The "new" thing is not that Big Media is composed of leftists and liars (but I repeat myself) ... the "new" thing is that the internet facilitates catching them in their lies.
What caused American media to become what they are today?
That answer is much more complex than their being dishonest.
The type of people who grow up wanting to be journalists are those that somehow ‘want to make a difference’ in society, without having to actually work hard learning and practicing engineering or science. Then they are indoctrinated in thoroughly liberal colleges into their being sure conservatives are selfish bigots that are against to wellbeing of the downtrodden and who would really prefer to be slave-owners.
Then these liberal leaning kids, with solid liberal education in journalism are hired by rich liberals who use these subjective thinking journalists to increase their power.
A similar negative occurrence happened around the late 1800’s into the early 1900’s, called yellow journalism. It too was based in liberal progressivism. The public rebelled against the Yellow Journalists and drove it underground only to reemerge under FDR and LBJ, now reaching it peak under the anti-American muslim halfrican.
You think it has always been this way?
In this 1920’s? The 1930’s? 40’s?
When? Why? How?