How do you expect journalists to be able to figure out the truth? And how do you not see them as a single point of failure? Let's take an example from the past. The Vietnam War was started because of a false flag. [1] This was a time when there was a much more adversarial relationship between the media and the government/intelligence agencies than there is today. But even in that context, they mostly unquestioningly reported the lie. Because how else could they have known?

In modern times I'll again take the glass half full side here. The truth of things tends to come out over time, because it's the only 'narrative' that can hold up under scrutiny from any angle. And even in the anonymous internet age, there's still the issue of reputation. It's perhaps more important than ever now a days because you can look at some entity's predictions or statements from one time period, see how it played out over the next e.g. 6 months, and see whether they were onto something, or blowing smoke.

I think this is why it's so hard for the government to drum up support for war now a days. They have no ability to control the narrative and so framing invading some country half way around the world as being 'defensive' is a narrative that usually collapses in rapid order. Even during Vietnam it started becoming clear that the narrative around the Gulf of Tonkin was dodgy, but it's a process that took years. By Iraq we were down to lies starting to be exposed within months. Now a days it'd probably take about 24 hours, to the point that with Iran didn't even bother with trying to manufacture consent and we saw the result of that a few days ago.

[1] - https://en.wikipedia.org/wiki/Gulf_of_Tonkin_incident