> Signal requires phone number in order not to store your contact list on their servers.
That does not make sense. There is no relation between 'using phone number as id' and 'storing contact list on servers'. E-mail and same other communication protocols also do not use phone numbers and do not store contact list on servers.
Yes but do they offer the same experience? Signal figured out that you probably have a list of contacts that you want to talk to. If they use mobile numbers as identifiers then they don't have to keep the contact list - it's already there on your phone. IMHO it's a good compromise.
I'm not an advocate for Signal, but I totally get this approach.
That does not make sense. There is no relation between 'using phone number as id' and 'storing contact list on servers'. E-mail and same other communication protocols also do not use phone numbers and do not store contact list on servers.