I mean, a phone number is an arbtrary sequence of digits. I'm very happy to use a chat app where I say to someone 'what's your username?'. I'm not giving a cha

I mean, a phone number is an arbtrary sequence of digits. I'm very happy to use a chat app where I say to someone 'what's your username?'. I'm not giving a chat app free access to all my contacts - and that includes things like Whatsapp