The Hive Authentication Service (HAS) will probably be the first step towards mass adoption. The easier the usage (including the login process), the more people will use it.
And if I may write down a suggestion, then I would like to mention SMS confirmation. This works on many websites. You receive an SMS with a code, and you confirm your login with that code.
Why add another level of confirmation? Not really needed with HAS;
That being said, it's up to the App or the PKSA to provide such a feature and take charge of the related cost.
For additional/more security. MFA (Multi-Factor Authentication).