Virtual Identity Dialogue

My colleague and friend Manny Fernandes asked me "hey if the DB lets you manage users with AD - why do you need EUS?"

The simple answer is that no - it doesn't replace the need for EUS because it doesn't cover all of the use cases EUS does.

Database Windows Native Authentication provides this:
If user is a member of AD Group ORA_DBA - they have SYSDBA privileges
If user is a member of AD Group ORA_OPER - they have SYSOPER privileges

Otherwise you need to manually create each user in the database and set them up to be identified as "external" though you can use the Oracle Admin Assistant for Windows to map AD groups to Database roles.

And - this is all restricted to just database running on Windows.

EUS in contrast provides
Ability to map multiple users to a shared schema 
Ability to map members of enterprise LDAP groups to DB roles
Is not restricted by any OS (though does require OID or OVD)