this is a new thing,

I guess you don't remember the garbage they were peddling in US media back in the 80s and 90s?

From wikipedia:

First presented in their 1988 book Manufacturing Consent: The Political Economy of the Mass Media, the propaganda model views corporate media as businesses interested in the sale of a product—readers and audiences—to other businesses (advertisers) rather than the pursuit of quality journalism in service of the public. Describing the media's "societal purpose", Chomsky writes, "... the study of institutions and how they function must be scrupulously ignored, apart from fringe elements or a relatively obscure scholarly literature". The theory postulates five general classes of "filters" that determine the type of news that is presented in news media. These five classes are: ownership of the medium, the medium's funding sources, sourcing, flak, and anti-communism or "fear ideology".

It did intensify after 9/11 - but it was only an intensification of what was already there.

many people weren't around then, 11-9 was more than 20 years ago

It's an interesting quesiton. I would argue the launch of USA Today followed relatively closely by Fox News is what started it.