The history of "consensus reality" is mostly the history of who got to enforce the consensus, and who didn't. If you grew up listening to Cronkite what you got was a sense that you knew what was going on - that's how it feels when you're in the hegemonic bubble. But if you've been outside it, you know how the illusion of a Potemkin village breaks down the moment you step off main street.
What's changing is that the mainstream view of what truth is was only made possible by the concentrated power afforded to television broadcasters during the middle to late 20th century. It was a product of a system few had choice in.
The internet didn’t create plural epistemologies, it simply showed you that they existed and always have, even at the heyday of broadcast tv. Of course, there are dangers, but let's not confuse danger for decline or loss.
"Who gets to decide what’s true?" was never a solved problem; we just couldn't hear other voices over the sound of The News.
The call to action isn't to revert to the golden age of epistemic monoculture. Are we truly aware we're asking for manufactured consent? Of course not. The call to action is to build skills and habits for reasoning when we're bombarded by noise and irreducible disagreement.
That's not collapse. That's what growing up looks like, for a civilization. We stop waiting for another Daddy Cronkite to come home and do the job for ourselves. The cure to epistemic anxiety is not the restoration of the hegemony. If he taught us well, we should be able to do it for ourselves.