agexpert and user

A question related to the ag expert profile (agexpert) and user profiles of Drupal.

I am working on further integration of users with the agexperts for ease of users, and admin (roles, user rights) and re-using content (e-mail address, Skype address). Doing that now via entity reference fields, as node references are no further developed.

Why was the choice made to make a separate content type of agexpert? The custom ag-fields could also be added to already existing user fields. This way I should not have to combine content via reference field, saving work and server capacity.