I don't see it either.. maybe a Signal employee posted this comment to try to justify phone number collection because they can sell those at a premium (or a secret order from the Gov. forces them to do it).

Also, what I want is accounts protected solely by username and password (actually, just a 50 character password without login would satisfy me)... this is one reason why I am slowly moving away from gmail. 2FA doesn't help me because I use my own device to login and if they get compromised, I am screwed either way.