Most users do live with a single device. If they have a work computer, they also have a work email (the client of which is unfortunately probably already opened

Most users do live with a single device. If they have a work computer, they also have a work email (the client of which is unfortunately probably already opened for other reason when they want to login to the site). The most-devices people I know are those who have a laptop, phone and tablet. That's it, I literally cannot think of anyone I know with more then this, and most of those with tablets are using it for games or reading or for the kids. Magic links are indeed the best solution for the average user. Type in your email with autocomplete, get a notification from the mailbox, click, click, and you're in.