On the other hand it reads your whole address book and in Europe you have to ask everyone on your address book if it is okay to send your data to Facebook (except those who are also using this app), otherwise you’re breaking laws.
The reality: it’s fully ignored in nearly any case, because
a) people don’t know or
b) people don’t want to do harm to friends and family or
c) they’re using WhatsApp themselves.
The API work is not done yet. Things that will come at time. Currently this happens to everything except the camera app.