NSA may have the best codebreakers in the world, but they don’t have access to all of the different database schemas that all the various private companies use.
Look at a SQL table (or for that matter, any relational database). Those tables have various columns defined, and different views, and different joins, and all sorts of cross referenced data within the database. To say nothing of indirect and direct codes and shortcuts,
It’s one thing to intercept network data calls – the NSA does that well – and quite another thing to be able to data mine in a complex SQL or other database structure. And these database structures are very proprietary and non-standard—each company defines the for the specific uses that their applications need.
The bottom line is that NSA has to go to the companies to understand and make use of any data. A hard drive (or a server farm) full of data is worthless unless you know how it is structured.