Well (a) SMS doesn't work with me (b) A lot of SMS messages to my Twilio numbers get dropped so it's a shitty protocol (c) SMS based on a SIM card number can't

Well (a) SMS doesn't work with me (b) A lot of SMS messages to my Twilio numbers get dropped so it's a shitty protocol (c) SMS based on a SIM card number can't be used if the SIM card is changed (d) SMS is limited in how many bytes it can send while with e-mail you can easily send megabytes. If it's too formal that's their problem. Also, I would never give one of my 10+ phone numbers to someone who I wouldn't give an e-mail address to, except maybe my one junk/spam number.