Comment by heavyset_go

Agreed, but people are going to people and will use phones, anyway. Might as well not include identifying information during registration.

Signal is a desktop app, as well. Even if you wanted to run it on Qubes in a Faraday cage, you'll need a phone number to register to use the app.

In the ideal situation, no one would be using Signal, phones or computers, the design of the internet is inherently identifying and non-anonymizing.