We can derive wry amusement from various US agencies' repetitive insistence that PRISM etc. log only call metadata and not "what was said". What they don't say is that NSA already log "what was said" directly off the fiber, and they only need Verizon's metadata to discover who said it. What makes it amusing is that to collect "what was said", they use a (lower-case) prism to split each fiber's light beam into two.
As a general rule, when a wide variety of unelected officials and their various press and elected mouthpieces repeat an assertion ad nauseum, it might or might not be technically accurate, but its purpose is always to distract our attention from a truth that, come to light, is much, much worse.
The overarching truth in this case is that whatever use surveillance may have for foiling nefarious plots, its chief value, everywhere and always, is in support of extortion. It's the basic currency of corruption. Extortion can force court judgments, congressional votes, cabinet and judicial appointments, bid selections, and resignations from elected office. Any discussion of pervasive surveillance that doesn't mention extortion is another distraction.