Pity that e.g. Apple doesn't implement some special configuration for the privacy conscious users, which would allow me to: "give to the app1 only contacts a, b, c" and "give to the app2 only contacts e, f, g." At the moment all the apps that I use and which insist on access to the contacts get all the contacts you ever stored on your mobile phone. The apps should also not get my notes to the contacts, the birthdays of the contacts etc. Ideally Whatsapp should get only phone numbers, and only these that I want to give.
In Android, Google should (it it hasn't) also implement this as a security feature, the benefit for them is: limit the access of the user's contacts to their competitors, by those users who'd use the feature (I don't use Android, is there something like that?).
Anyway, by using WhatsApp, since lats year you give Facebook all the phone contacts which they will store and match even if you didn't want to give these to Facebook for Facebook.com or whatever.
"“Privacy is incredibly important to WhatsApp. It’s why we collect very little data, and encrypt every message,” a spokeswoman for WhatsApp said."
When "a little" is all your contacts in the phone, it's more than a little for Facebook.