- Great way to confirm if email address is valid
- People tend to use bad passwords
- People tend to forget passwords (you need to write whole password recovery, etc)
- You always have your smartphone with email close to you
- It's way easier than 2FA with Authenticator and cheaper than SMS
- You limit password sharing for your service
This is a great list of reasons it’s better for the provider of the service.
But it isn’t better for the user of the service.