The Graphics User Interface is missing the Resource -> <machine> -> Accounts -> Add button.
Problem:
After a user is granted the "Add Account" privilege on a resource, but the "Add" button does not appear in the GUI for the Account on that resource
Resolution:
In addition to the "Add Account" privilege, the user must also be a member of the Administrators role. Once user is added to that role, the "Add" button appears in the GUI: