Why does Human Capital Management Application Administrator require a View All Data role?

Summary

If the Human Capital Management Application Administrator job role is used for HCM setup tasks, why do security profiles need to be assigned via a Data Role?

Content

In the Securing HCM Cloud guide, it recommends that a View All data role gets created for the Human Capital Management Application Administrator job role.  We've used just the job role to access the HCM setup tasks and sandbox administration without issue. Why does this job role need security profiles associated with it by creating a data role?  Is that absolutely necessary?