Social networks is a concept that goes far, far beyond so-called social media. You might want to read up on how social network theory is used, for example, in a military setting to track down terrorists (cf. my links above). It was used to great advantage in Afghanistan, for instance. And they weren’t looking at Facebook likes. You would be stunned at what social network theory, applied to your metadata, can tell you about you. - probably more than you know yourself.
You missed the point. Without doing it digitally, they have no meta data to work with. If this is all they are employing, then it is very easy to render them, blind.
I have a military history of crypto repair and analysis to the point of being on a team learning all of the new toys from the actual engineers who designed them from inside all of the skunk works that employed them. I would wager that I know far more about the methods they are using than you can even imagine.