I have a question. Why not SMS? Is it because sending an SMS globally is more of a hassle then sending email? Or that with email we assume the entire channel ha

I have a question. Why not SMS? Is it because sending an SMS globally is more of a hassle then sending email? Or that with email we assume the entire channel has some protection layer to it, where as in SMS the security is due to the fact that we're using an entirely different channel? Simply intercepting an SMS (if you actually manage to do that) won't be enough as you would also need the username. In the email approach, don't most places use your email as a username?? I am just talking generally, not specific to this app