Well, Firefox _could_ passively observe your life and update your preferences (better than Facebook or Google do, if it's the primary browser - since they'd obs

Well, Firefox _could_ passively observe your life and update your preferences (better than Facebook or Google do, if it's the primary browser - since they'd observe you across all activities). It's just that it wouldn't need to share that information with anyone except you - it stays local. That's what I love about the system - you can be as targeted/"privacy invasive" as you wish without actually invading anyone's privacy, since people stay firmly in control of their own data. To add to that, "private mode" would actually do what people expect it to do - keep them anonymous on the web, and not leak sensitive/ embarrassing information about themselves.