So you can identify yourself and setup an account that tracks and stores your personal data in a way that's intended for you. It can also hold important data about you like stats from devices, DNA information and your CV. You could also questionnaire yourself to see where you fit in with generalized stats.
So you can data mine yourself in one place and you can get tips (with some very personal ethical and localized advertising) with no shared personal information that hasn't been specifically authorized by you.