I agree here, but I think there is a simple and obvious middle ground. Allow for contacts to be connected through the address book (one time or continuous) but ALSO allow for contacts to be added without phone numbers. This could be through usernames or one time codes (like a QR or temp username). But importantly, there needs to be chat level handle specification. I don't want all my contacts to know I'm Godelski and I don't want all my contacts to know I'm [redacted]. I might also have other handles. It shouldn't be a difficult challenge to handle chat level handles (with a default option). It seems like just such an obvious solution. But I'm not a security person so maybe someone can tell me why I'm being naive.