One of my favorite journalists is R. Emmett Tyrrell, head honcho of The American Spectator, quite simply the best journalism magazine currently extant. As usual, Tyrrell gives us an insightful tour of how the mainstream media became the lamestream media, under total domination by leftwingnuts for the "news."
I doubt that journalism was preordained to be dominated by liberalism. There was a day, before the New Deal, when there were plenty of journalists who were not guided by left-wing ideas or any motive at all. The clever journalist, usually, just wanted to get a good story. Yet the New Deal came along, and then World War II and finally, television. At first, it was humanitarian to be in sympathy with the New Deal. Then it was patriotic to be in sympathy with what was a growing homogenization of views amongst news gatherers. Finally, it was good sense to be a liberal newsman. By the time television came into its own, liberalism was the corporate mentality of the news-gathering business. Hence, you can take a television news gatherer or a print news gatherer and plug them in interchangeably.And from liberal domination of the media, it's only a very short step to the Vast Left-Wing Conspiracy that brought Barack Hussein Obama into the White House. Read the whole thing, it's worth your time.
By the 1990s, this corporate mentality had begun to change. Rupert Murdoch and Roger Ailes saw a market. They dissented from the media's corporate mentality and presented the news from a conservative perspective. Talk radio came along and presented a conservative talk venue. Now Fox News alone brings in more revenue than the combined revenue of CNN, MSNBC and the network news shows on ABC, NBC and CBS. The corporate mentality suddenly was in trouble.
Instead of breaking up along reasonable lines, it has tried to remain coherent and viable against the odds. While Mr. Murdoch and Mr. Ailes at the Wall Street Journal and Fox have employed ideologues and entertainers, the media's stalwarts are all "true" journalists who have continued gathering the news, pronouncing on it and covering their gluteus maximus when some poor wretch such as Dan Rather proves to be an embarrassment.