And therein lies the problem: gathering information and building up profiles, if not done in a sensitive and transparent manner, can look an awful lot like snooping.
Everything is now being saved and correlated, and many big-data companies make money by building up intimate profiles of our lives from a variety of sources.
There is probably a sweet spot of mid-sized apps that have particular enough user profiles, but a lot of that kind of user, that are worth building custom campaigns for.