For Android:
there are still other identifiers in android (eg advertising ID, android ID) that tie things together
I use XPrivacy. It (and other alternatives like PDroid, App Ops, Privacy Guard, most require root or Xposed) allows you to block certain items from applications (eg IMEI, access to google accounts, contact list)
The Facebook app installed on my device does not have access to my other Google Accounts or contacts list, can't spam me that much