It's a strategy that, as Borchers notes, suggests the White House isn't really interested in litigating the details of the reporting, but would rather use the stories to label the media the enemy, after the fact.
But perhaps it's also because they realize they can't really litigate the details -- that they don't have a leg to stand on.
Part of the problem with shooting down negative stories before they publish is that you actually have to deal in specifics. When reporters ask for comment, and you push back, you have to make logical arguments about the details contained within the story.
The White House doesn't really do this, even after the fact. The one specific example they cite as proof of "fake news" was a botched pool report that said a bust of Martin Luther King Jr. had been removed from the Oval Office once Trump moved in. They pointed to this over and over again as proof of the media's malfeasance -- despite the fact that it was quickly corrected and was the result of an oversight on the part of the pool reporter.
Another example came this weekend, when White House press secretary Sean Spicer complained about the New York Times getting his birthplace wrong. Aside from the irony involved in this coming from a White House whose president frequently questioned Barack Obama's birthplace, it turns out the Times sought comment and got none.
These factual complaints are the exception rather than the norm. Most often, the White House just dismisses an entire story without saying why.
In his speech Friday at the Conservative Political Action Conference, President Trump berated the media for using anonymous sources and pointed to a Washington Post story that used nine anonymous sources. The story in question was the first to report that Trump's national security adviser, Michael Flynn, had spoken with Russia's ambassador to the United States about sanctions when he may have been legally prevented from doing so. And it not only hasn't been proven false; Flynn and the White House have basically confirmed the details of it, and Flynn was fired because he had misled the White House about having discussed those sanctions.
If the media really is pushing "fake news" via anonymous sources, in other words, this was a very curious example to cite. Apart from that, Trump spent 12 minutes deriding the media in broad terms without any real specifics.
Of course, just because a report hasn't been proven false doesn't mean it's necessarily true. Reliance on anonymous sources may be necessary when dealing with insular political institutions, but it's best avoided because it doesn't provide for accountability for those providing the information. And by using anonymous sources, the media certainly opens itself up to criticism.
When we publish something, we expect it to be picked apart. And it would be nice if the White House spent more time actually doing that rather than just dropping a "fake news" or two and walking away. We would welcome it.
Even people who are skeptical of the media should hope for this kind of back-and-forth that is all too often almost completely absent from the Trump White House's press strategy. It may not suit their political purposes, but it would be great for democracy.