Earlier quoted context omitted.
The biggest messaging platform on the planet uses phone numbers as user ids. It seems very unlikely a majority of users see this as a showstopper.
Those users do not use it a secure messaging platform. The see it as a way to get around SMS fees. The majority of Signal users are likely privacy- and security-focused, and chose to use signal because of the features it provides on those fronts. Comparing those two userbases doesn't make much sense to me.
I think it's really you who is making the extraordinary claim here and you should be providing the evidence. Signal's goal, as has been repeated many times in these threads is to replace SMS and other less-secure forms of messaging for as many users as possible, not to cater to somewhat off-the-beaten-path concerns over phone numbers. They are aiming for users of messaging. And they are making the very reasonable inference that most of those users are not hung up on identifying themselves with a phone number.
Additionally, if Signal's current users cared about the phone number thing that much, they wouldn't be using Signal to begin with. Where's your survey data that says Signal users just can't stand the phone-number-as-id thing?