I have but one question
If a company does not SELL client information but only gives it away, that is still illegal too, no?
The answer should be yes, but that would put every company which allows WhatsApp potentially at risk. I suspect Zuck could get quite upset about that (in his very private I-bought-out-all-my-neigbours mansion).
For your Europeans out there, that IS already illegal in Europe if the address book on the phone in use contains but one personal contact detail of someone who has not goven explicit permission for this to happen..