adding extra work or school account in Win10

I have a question about Windows 10  box that is joined to Azure AD

Why should I add user at # Windows 10--> Settings --> Accounts --> Other users --> Add a work or school user

Even without adding any Azured-AD account in above place, that user can easily first time unlock the device by putting his UPN and password on the windows 10 unlock screen.

So what I am buying by pre-adding the users through above menu item.

Thanks.