I think that's a good description of the media even today. Actually, Owen Chadwick points out that the press of the 19th century was both a pulpit and a growing power with built-in liberalist bias. I think that we can still claim that this remains largely true of the press and other media today. This bias, in a sense, remains no matter what its orientation happens to be. Permit a comparison with advertising.
Advertising is an extremely important element in our society today.
We would not know how to live without it and it can be of great benefit. There's no doubt about it. But there is something built into advertising that is seldom adverted to, but it's taken for granted. That is the perpetual appeal to our likes and dislikes, to our real or imagined needs and urges. And that is built into our advertising , and whatever else you say about it, it's there.