Those are the conclusions I've drawn as well. The harder question is what do I do about it? And funny enough, the most reasonable answer I've been able to come up that actually works in practice is......ignore it.
Well, you can't quite "ignore" it because the foundation of all modern life outside your immediate location is someone else's report/anecdote. (If you want to go to the Basement, it's one more reason you can't ask your Deity for immediate verification of the facts!)
So then what Wikipedia made famous is "Citation Needed" as the very rawest of the raw stopgaps from stuff like the Aliens in the next thread over from the Guardian.
So then the entire concept of news is, underneath all the kaleidoscope spin doctoring, "something" is supposed to have happened. So if you tell anyone else, you basically get handed "Citation Needed".
But when your *Citation Changes*, they don't sweetly do Version Control like all you programmers do for a living. They just change it at will.
So yes, the more rampant this gets, it is absolutely PAST the slippery slope, because then you can't believe anything at all anymore, ever. Once you get past cute little bits of "common sense" like gravity, then it goes all Alice in Wonderland and it's almost not possible to function if the minute you pointed at a source, it has changed and then you can't prove why you're the only one that you can get hold of that ever saw the original version (versions!).
Cue all the SciFi stories - this is "locally" close to "alternate timelines".
It gets very very fast to a Matter of Degree.
After all, Obama isn't President. What? You are deluded into thinking he is? Why, because he said he was in the oath on the lawn, you think that matters? Who told you that? Were you there? What, you think the "nice steady stream of Obama-y things" means something?