The media has been in the bag for Clinton, Obama, and Lincoln too

Even just in my own areas of expertise -- labor markets and health care -- it is easy to see how reporters and editors of "the news" have been promoting Democratic-party policies.  It's not just convenient ignorance about how incentives work.  Many times they know very well but are silent about it for fear of blemishing the narrative, even while proclaiming to their readers that they tell the whole story.

But this is nothing new.  As Harold Holzer found,

Lincoln alternately pampered, battled, and manipulated the three most powerful publishers of the day: Horace Greeley of the New York Tribune, James Gordon Bennett of the New York Herald, and Henry Raymond of the New York Times.

Lincoln authorized the most widespread censorship in the nation’s history, closing down papers that were “disloyal” and even jailing or exiling editors who opposed enlistment or sympathized with secession. The telegraph, the new invention that made instant reporting possible, was moved to the office of Secretary of War Stanton to deny it to unfriendly newsmen.

As long as the government controls significant resources, the consumers of media will want to know what the government is doing, and the government will sell access to that information to "newsmen" in exchange for favorable coverage.

It isn't merely about changing a specific journalist's mind.  It is also about helping those who are already inclined favorable to earn more profits than those inclined otherwise.  Media market entry and exit takes care of the rest.