Well, depends on your historical time-scale, and what you mean by "the media", doesn't it? If you mean the corporate media, then "have become" is wrong, but if you mean the entire media, including once lively labor newspapers and independent radio programs, which have all but disappeared from mass circulation, then I don't find it terribly misleading. Chomsky and Herman note this deterioration at the beginning of their book *Manufacturing Consent*. The labor newspapers may have been ugly in all sorts of ways, but hey, at least it was the voice of (some of) the working volk, was it not, Doug?
Of course, McChesney is well-known as the author of another outstanding book, *Telecommunications, Mass Media, & Democracy: The Battle for Control of U.S. Broadcasting, 1928--1935* (Oxford University Press, 1993), which looks backward quite a way for the undemocratic slant, so I wouldn't blame him so much as the book-jacket-blurb ad folks for the misleading blurb.
Bill