hook_field_extra_fields for additional profiles

I have created a new profile and I am wondered why the newly created profile is not shown in the fields overview in /admin/config/people/accounts/fields. I found out that is caused by the hook_field_extra_field function. My use case is to add a additional multipage for this user profile. For this reason I created a patch which offers the option to move the newly created profiles into field groups via the admin menu. Maybe this is a usefull addition.