In practice, users seem to get confused and then send emails asking why they can't just use passwords. Example edge case: it doesn't work well for people who d

In practice, users seem to get confused and then send emails asking why they can't just use passwords. Example edge case: it doesn't work well for people who do things like sign up for your site with a secondary email address, and then try to access your site from a computer/device that doesn't have access to the secondary email account. I think that Slack does it the ideal way -- you set a password, but you can always request a "magic link" to get into your account via an email link if you don't have easy access to your password.