If there is some recent revelation that makes phone numbers all of a sudden a secure, portable and censorship-resistant identifier please link me that.

Until then I'd prefer to not have my private communication determined by telephone companies that often have not cared for either security, censorship or privacy. Regardless of signals e2e encryption having my access to the network determined by a telephone company is not the right way to go.

For a nominally privacy focused app, for them to literally alert people to my new Signal account I'd gotten to securely message someone violated all trust I had in them. What's to stop someone from just adding a Contact for every single valid phone number on their phone and then getting an alert for any time anyone makes a Signal account? I may as well just use Facebook then.