This is true, NSA has everything and they keep everything except what they don't need. But what they still have to find a way to get at the information that leave a legal non-contaminated trail to that information so that it can be used in court as evidence. It doesn't matter what you know if you can't use it. "fruit of the poisoned tree." That means working it, finding people to flip, to give testimony, so tht you can get to that information as corroboration for crimes committed. Laws and stuff. Mueller, RR and slow walking has a purpose. Flynn is key to a lot of this as an eye witness but so is every other person flipped that holds their own piece of the puzzle.