The protection you offer even in the ideal case is worthless when there isn't trust that a journalist will bend to political pressure, financial incentives, threats, or to push their own or their publisher's agenda.
Saying that people need to "crtitically read" is just intellectual grandstanding.
Not with the example you've given. Investigative journalism is one form of journalism. I won't attempt to define journalism except to say the forms its stories take do not include posting a tweet in reference to someone's sentence fragment from a Facebook status. That may be a part of the "raw material" of a story that covers how conspiracy theories begin and spread. But neither that raw material nor the journalistic stories which essentially just tracked the effect of a wild conspiracy theory on a national election are examples of investigative journalism. (There may be pieces of actual investigative journalism wrt Pizzagate, but I haven't read them.)
But let's say we compare Seymour Hersh's story on the killing of Bin Laden and some random Facebook fake news story pretending to be a piece of investigative journalism. At least at present we're not at a point where a fake news artist can do a good enough job mimicking a piece of serious investigative journalism. But disregarding that, the main difference there would be reputation.
But that isn't a small difference. "Reputation" covers a lot of ground-- it includes the publication and the journalist. It also includes the age of the publication, its intended audience, its business model, and even whether the name of the publication appears to have been chosen to be similar to the name of a more reputable publication.
That certainly doesn't mean I reflexively accept all of Hersh's claims-- I do like other non-experts on the subject and withhold judgment until other experts begin to assess the veracity of his story over time. But it does mean that I can reject out of hand the viral Facebook link to some url that looks like "cbsnews.com" if you squint. I can save time and not read it at all based on reputation alone.
> And when trust in the press is lost what separates the curds and the whey is evidence which a fabricated story cannot provide.
It depends on why the trust was lost. If it was because a critical mass of journalists' track records got worse over time, then you're right.
On the other hand, if it is because a critical mass of readers can't tell the difference between a Pulitzer prize-winning investigation of media corruption and a click-bait website on Facebook, asking them to "weigh the evidence we're showing you for yourselves" isn't going to solve anything.
Just spitballing here.
Since that is probably the most important and consequential type of journalism, I'd expect facile attacks claiming investigative journalism "isn't transparent" if this takes off.
The obvious and easy protection against such an attack is to critically read multiple sources and be familiar with journalists' track records over time. So I'm afraid we don't have workable protections against this attack atm. :)