The danger with "fake News" is not new. It has been around for at least 60 years that I know of, and is only recently been given this new name to make it seem new. (See for instance, "bubble" vs "echo chamber" for how old things get new names by new generations just discovering them, thinking they are new and earth shattering.)
Propaganda is older than dirt, and spreading false news reports is just as old. Usually this was limited to things involving troop movements and other "get them where we want them, not where we really are" type things when reviewing ancient history, but still there, and a prominent tool of statecraft.
These days, given the rise of "high information", it is much more in common with general propaganda, where people have become intellectually isolated, self-segregated in what information they are willing to accept as truth, and this has created a (wider) opening for various interests and groups to manipulate and control people via the information they already preferentially consume.
This is not isolated to just one group in current politics. It would be foolish beyond measure to leave that tool alone while the others are using the shit out of it.
That's why we see lots of very terrible attempts to connect the DNC hack with the discovery of malware of russian origin, despite the obvious holes and problems with that forced connection. (which is why most of it has been retracted by the MSM once they were called on it.)
Fake news is not new. Its flagrant use as a general propaganda tool is somewhat new-ish in terms of the scope it is being used with-- but again, general propaganda is not new either.
It is interesting to see which outlets carry such stories, as it betrays the endpoints by which such interests present their agendas.
Some, like Breitbart, are flagrantly obvious, but not always so.