Earlier quoted context omitted.
I don't need a phone number, nor do I need to upload my contacts' phone numbers[1], in order to use Matrix. [1]: I work around this by running Signal in a work profile with no contacts. So it's... kinda sorta optional, but in practice there are many caveats and complications that make it effectively not. Certainly not when we're claiming it for average users, which is Signal's argument for using it.
I’m not a Matrix user, but it seems like Matrix does in fact handle contact metadata: https://matrix.org/faq/#what-is-an-identity-server%3F I think there’s a difference between what you’re saying, which seems to be that you personally don’t upload your contact metadata to Matrix, and what I asked / the previous commenter was describing, which is the idea that there are messaging platforms which have decided to not su…
What Signal does is 1) require your phone number, 2) automatically upload every phone number in your contacts, and 3) send a push notification to people on Signal that have uploaded your number in the past that you have joined.
It's a world of difference. And a huge breach of implied trust for multiple people I've known, who joined and immediately uninstalled when they found out a bunch of random people were notified.