It's a similar phenomenon to the "post-Hilary" world of the Wikileaks email docs. People assume there was hard evidence proving a criminal conspiracy by the DNC to rig the election somewhere in there... mostly because that's what other people told them. Not because they've bothered to look.
People's cynicism has led them to put more trust in the metafictional reality of leaks than actual reality. Which, ironically, makes them easier to manipulate even as they believe themselves to be somehow above indoctrination and control having reached enlightenment through the "Snowden revelations."
I agree that the sentence exactly as you've written it describes a possible conspiracy theory that some people may hold.
I also believe you're hedging a bit-- it's possible for people who didn't follow the leaks to infer from your exact wording that a) NSA did not access those databases at scale using the PRISM program, or even b) NSA did not access those databases using PRISM, or maybe even c) NSA did not access those databases using PRISM or any other NSA program. None of those are true.
Here's something relevant from Wikipedia about PRISM:
> Documents indicate that PRISM is "the number one source of raw intelligence used for NSA analytic reports", and it accounts for 91% of the NSA's internet traffic acquired under FISA section 702 authority."
Can you speak to the veracity of that sentence?
Would you consider that as misguided? It certainly encourages a general distrust of all those company logos in the slides.
It leads to things like people implicitly trusting DDG because they weren't on the PRISM slide, or implicitly trusting Facebook and Reddit because they aren't the "mainstream media."
You're supporting my point rather than refuting it, in that you appear to have drawn an arbitrary line in the sand and decided to doubt everything on one side and believe everything on the other. That's not a rational point of view, it's religious dogmatism.