This affected people who never even used Facebook. It would tag and track your presence in photos even if you had no Facebook account.
whatsapp and google system apps scan your contact list every two seconds (not hyperbole) and send the diff to their servers. if you are in someone's phonebook, you're very well cataloged on their systems. and those contact entries tie phone, email, name, other grouping, association list by crossing lists, address, aliases, etc.
they have to claim they don't map those identities for ad targeting, but everything else they can claim you "asked for it" like suggesting new contacts to add is fair game.