> Moxie seems to insist that the only way to build a successful service is using telephone numbers, but clearly that is false as the world's largest unencrypted messengers--which should be the enemy, NOT WhatsApp!!!!!!!!--do not use phone numbers as identifiers and allow users to hide them even if they are collected.
I don't think Moxie insists on this. I remember reading this on the Signal blog[0] a few years ago:
> Social apps need a social network, and Signal’s is built on the phone numbers that are stored in your device’s address book. The address book on your device is in some ways a threat to the traditional social graphs controlled by companies like Facebook, since it is user-owned, portable, and accessible to any app you approve. For Signal, that has meant that we can leverage and contribute to a user-owned portable network without having to force users to build a new closed one from scratch.
> However, many Signal users would also like to be able to communicate without revealing their phone numbers, in part because these identifiers are so portable that they enable a user’s conversation partner to contact them through other channels in cases where that might be less desirable. One challenge has been that if we added support for something like usernames in Signal, those usernames wouldn’t get saved in your phone’s address book. Thus if you reinstalled Signal or got a new device, you would lose your entire social graph, because it’s not saved anywhere else.
> Other messaging apps solve this by storing a plaintext copy of your address book, social graph, and conversation frequency on their servers. That way your phone can get run over by a car without flattening your social graph in those apps, but it comes at a high privacy price.
[0]: https://signal.org/blog/secure-value-recovery/