[Xylakant]

practically all website that use an email as username nowadays require email confirmation, so already include the context switch. Because in the end, sending an email is the only way to verify that the email address is correct and you don't want an incorrect email address in your database if you rely on that communication channel.

Now, if you have accounts in places where email addresses are not required and usernames take the place, the calculus may change. But using the context switch as an argument here is just weak.