[grammers]

Not sure, but it seems like from a usability perspective it's easier for apps to 'just connect' people in your contacts via the phone number. From a privacy perspective, though, it's much better what Threema does.

That's also why I use Tutanota, one of the very few mail providers that you can use without a phone number.

[godelski]

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.

[lxgr]

> [...] 'just connect' people in your contacts via the phone number [...]

Threema also allows that.

I think they really nailed that aspect: Tie the primary identity to a key, not a phone number, and then add a discovery layer on top of that.