The problem is that he will have an always more accurate profile of you. Your incomes/expenses tell a lot about you, some info that interest a lot of people...
The consequence is that FB will sell your always more accurate profile (or give it to the NSA :-)
Exactly !
We are less mature, but we have a very different approach.
1/ cozy is a PaaS : plateform as a service : you develop in your language (node.js, ruby, pthon... only node for now) and your app is automatically deployed on the user's instance (if he ask to, of cours :-)
2/ data are shared among the apps : several apps can require access to your photo, contacts or mails or whatever : your apps are collaborating like on your smartphone.
For the better : if you quantify you can improve.
And for the worse : The NSA will spy our soul :-) (oups, it is already the case...)