I feel like if I were to make a service that required log in that's how I would do it, but with all the talking about it I've never actually seen it in the wild.
* B2B. The project is targeting companies where everyone relies on email.
* It is easier to implement. Compared to normal email/password-based authentication systems, it is almost exactly like the email verification step but it does not need any "forgot password" or "change password" functionality.
* Access tokens are temporary. If your DB ever gets hacked, the tokens are not valuable in the long run.
* Makes account reusing by multiple people more complicated. This is especially useful when your project uses seat-based pricing.
* Cheap "SSO". You can only use the service as long as you have access to the email address. This might be interesting for companies. People who leave automatically lose access (as soon as the token expires).
enter email address, get a link via email, click on link: magically logged in!
If so, that's exactly what I've discussed with various clients to implement for their projects, because I agree that in many cases it's a really nice and, as far as I can tell, safe approach.
Personally I really don't like it, because I have a password manager and I rarely have my email open in my browser. But for many, if not most 'casual' computer users it does seem ideal to me.
Even as a user, it's more friction than a social login or password manager. This is effectively what I needed to do when I used vatsim prior to using a password manager as they made you use a password set by the app that was 8 characters alphanumeric so I used to end up having to reset it a lot.
It also offers SMS based login in a similar manner where no passwords are involved and you just copy a 6 digit or so number from a SMS you receive upon clicking 'Login'
In India this SMS based login method without passwords is the norm for almost all locally developed apps I've used (despite SMS as the sole authentication factor being not really secure due to the possibility of sim swapping, etc).
Disney Plus (Hotstar) in India has recently started mandating users to switch to such SMS based single factor auth (from password based login), presumably to add friction for account sharers.
That's terribly annoying to me as a consumer so please don't do it.