The mainstream media panders to what sells eyeballs. Clickbait is cocaine for eyeballs.
Quality journalism? Who gives a fuck, this is the age of fake news. Sell those eyeballs, that's all that matters.
I know that's the Trumpian line these days, but it oversimplifies the problem to an unfair degree. The news isn't fake. It's just fast, there's more of it than ever for you to access (and, by virtue of limited reading time, ignore), and every level of aggregation you put between your eyes and the journalists has to filter somehow, and there are good reasons to do so by pageviews.
In the majority of my interactions with journalists, I've been impressed by how much background reading they're willing to do and how perceptive their questions have been; much as I gripe about science & technology journalists oversimplifying things and reaching too readily for movie references, I can't say that comes from their own laziness. The articles they end up writing have been entirely fair for their length and the requisite background, too, but few people most of read those articles, if for no other reason than that all the local news outlets are now competing directly with each other online and the sheer volume of information is unmanageable. So they get aggregated, over and over, which usually involves them being rewritten at least once for a bigger platform with tighter constraints on length and writing time. At every stage they're being effectively sorted by views, even if not consciously, both by search engines and simply by statistical laws. Plus which, we can hardly fault journalists for reporting things their audience is interested in hearing about, so that's another effective sort by views. By the time the news reaches your screen, it's more probably gotten there from successively larger platforms, and the game of telephone produced by repeated rounds of sorting and summarizing can badly mangle the original intent of the author on subtle points -- particularly since, in the Internet age, all of this is happening as fast as possible on an international scale. All of this assumes a totally neutral observer, too, when in practice the simple human tendancy to read what we like reading and the sorting produced by social media (even if you don't personally use it) combine to put us all in an echo chamber by default.
The upshot of all this is that there's still real news out there, and the mainstream media does a fine job of at least highlighting parts of it -- often you can get back to the original story just by clicking the embedded links until you run out of links. It's not so much the age of fake news, then, as the age of the news being as real as you have the time and inclination to make it. As for why people would rather complain about fake news than read real news, that's part of a much larger problem with the culture wars and expressive responding.
All of which is really to say, in the style of our time, that fake news will stop when we all quit trying to show how clever we are by complaining about it.