I think it's crucial for Gmail, because the popularity of email-based verification means that if you lose your email account you lose everything. Including the

I think it's crucial for Gmail, because the popularity of email-based verification means that if you lose your email account you lose everything. Including the presidency, in John Podesta's case! I also use it for Bitbucket and Githib, but I take your point and also hope it becomes a widespread standard.