This is by no means a very secure option but do you really care if your www.anime-planet.com or konachan.com account don't use 2 factor authentication.
Some websites just don't need such a high level of security plus you could argue they are probably less careful with your password than say Google is with your email.
Now it can still be hacked but you could argue this is probably an increase in security although it does create a central point of failure just like password managers.
Nobody says Google or Amazon should start using this but websites with a lower requirement of security shouldn't inconvenience their users unnecessarily.
If you're only need is to identify the user for something banal that couldn't do much damage if it gets hacked then this is a good solution.
Some websites just don't need such a high level of security plus you could argue they are probably less careful with your password than say Google is with your email.
Now it can still be hacked but you could argue this is probably an increase in security although it does create a central point of failure just like password managers.
Nobody says Google or Amazon should start using this but websites with a lower requirement of security shouldn't inconvenience their users unnecessarily.
If you're only need is to identify the user for something banal that couldn't do much damage if it gets hacked then this is a good solution.