I was going to bring this up, that they possibly can't sift through all the data but I stopped when they propped up their strawman.
It's akin to take a camera, getting in a car, and just filming through windows while driving across various suburbs for 24 hours. Sure you're invading peoples privacy, but one person having to sift through and catalog everything they see through a window is inefficient.
That's an analogy. Yeah, the US is illegally spying on every goddamn microbe in the USA, but they don't have the staff or capabilities to sift through every single thread, in that if your info is read off by someone, it'll mostly likely be a bot categorizing it. And if they focus on anyone, it's because they have reason to believe they may be planning or working with a terrorist-not just because you're an average joe.