First, the "also" is misplaced. Signal's telephone number requirement is a privacy feature; it's not that Signal wants your phone number, but that using phone numbers as identifiers allows them to build a social graph --- every mainstream messaging app involves a social graph --- without keeping plaintext contact lists serverside, which is what every other mainstream messenger does. That's not a small thing; the information in those contact lists is one of the highest priority targets for any state-level adversary.
I don't love the cryptocurrency stuff either. I'm not defending it. But "shot their credibility" is an overstatement.
Fair on both points. The “also” is misplaced as most users have zero problem with Signal processing their contacts. And “shot their credibility” was hyperbole. “Severely damaged, albeit repairably” is more accurate.
> Might be troublesome if you don't want the other person to know it's you, though.
You're mixing privacy and anonymity. Signal offers privacy from snooping, they have never claimed or tried to provide anonymity. Two very different use cases.
There are better ways to verify someone is who you think they are, e.g. asking them about an inside joke that you only told them in person at some point in the past, or what art you have up on the wall in your dining room.
Also, you might in some cases want to share knowledge or evidence without disclosing your identity, and phone numbers miserably fail for that use case.
