Because Whatsapp abuses contacts. I tried to send a message to someone without adding him to my contacts, but I did not find a way to do so in iOS. I had to add that number to my contacts and allow whatsapp full access to those.
And it's actually this information Facebook is interested in, to build the "social graph".
The content doesn't matter, it knows who you communicate with and how often, and that's already a privacy concern (wife wants to know if husband cheats on her with someone else? and so on).
But of course the WhatsApp CEO doesn't mention this ... much easier to say "we don't look at your content" to give it the spin they need.
"When you use WhatsApp and allow access to your phone book, we only see the phone numbers, not the name."
That's the weakness of current chat tools right there. They can't listen in but they do know when you talked to whom and how long, how often, etc. In fairness, Signal and Telegram are similarly dependent on phone numbers. The traffic might be encrypted but even just knowing who talked to whom, when is useful.
Yeah, this was demonstrated greatly in the Navalny/Bellingcat investigation of his poisoning: https://www.youtube.com/watch?v=smhi6jts97I . They bribed the appropriate providers to get phone call records and could see how the agents would be ringing each other and up the chain of command around the time of certain events. If an "enemy of the state" could do this, imagine what the state, or the owners of the data, could do.
Funny as if saying "just the phone numbers and not the names" should make us feel safe, Facebook already asks for your phone number, and could correlate your data that way.
i believe signal uses the phones contact list, but telegram manages its own contact list, and i can add telegram contacts contacts without knowing their phone number or adding them to my phone contact list. i can also block my number from being shared with anyone.
the only thing the number is needed for is to create a new account.
Assumably because they know who you talked to, when you talked to them and for how long and with an approximate location. They also have a good idea of what you were doing at the time from their cookies / "facebook integrations" over the greater internet.
Not sure if we can trust anything coming from FB or Google type of large corp under US national security surveillance capitalism state (with conflicting business model against user privacy) regarding what they really do with user data. Any corporation with association with the intelligence agency and the military industrial complex can not be trust.
Have warrant canaries at least shed any light here? It seems companies eagerly hosted them only for them to fall silent soon thereafter. Which, if accurate implies they have received warrants in short order.