I don't think anyone is claiming that this can replace the function that a validation email serves.
What this allows you to do is give feedback to users quicker. If a user signs up for your service and mistypes the domain name for their email address, they'll never hear anything from you. And if they don't know they made a typo, they'll just think that you have a flaky service. This lets you prevent that from happening.
What this allows you to do is give feedback to users quicker. If a user signs up for your service and mistypes the domain name for their email address, they'll never hear anything from you. And if they don't know they made a typo, they'll just think that you have a flaky service. This lets you prevent that from happening.