Just got the latest "Data Protection Agreement" from Intuit. Included in it is:
Intuit shall be the controller of Account Data and Customer Data when Intuit uses the Personal Information for Intuit’s own purposes, including for improvements in its products and presenting opportunities with Intuit to end users.
-also-
When acting as controller, e.g., for product improvement or to market offers to employee end-users of the Services, Intuit will individually determine the purpose and means of processing Customer Data and Account Data.
So the addition of the birth date requirement is so that they can market more products directly to the employees.
