The big issue I have with this is that facebook can already do this, IF a warrant comes from the government. The issue about being careful about using those me

The big issue I have with this is that facebook can already do this, IF a warrant comes from the government. The issue about being careful about using those metadata for friends/"you could know" (which was always terrible for me) and related functionality is legit though. They should give the user the option of opting out (ex: I don't want you to show my FB profile to people I only have in whatsapp/instagram). Even better, they should allow for opting in and opt out everyone by default.