This 'fingerprint' changes as you login in and log out of various services, so it's not very reliable for uniquely identifying users. Regardless, it could still

This 'fingerprint' changes as you login in and log out of various services, so it's not very reliable for uniquely identifying users. Regardless, it could still be used to profile you and then target content accordingly. For example, if you're logged into Hacker News, you're probably a programmer and you're probably more interested in an ad for web hosting than wedding dresses and visa versa for Pinterest.