individually, not important, together with a mass of collected data, over time, patterns emerge, those patterns can be everything from people, and people within your demographic, age, sex, location, race, education level, marital status, relationship status, and THAT is invaluable to corporations (and governments) in figuring out what to sell, how to sell it, and who to sell it to.
they say knowledge is power, and that's just what all this data from billions of different sources gives others, an overview of human interaction with each other, technology, and most importantly the things that motivate them to act.