DRM can employ authentication in itself, sure. But DRM is not about ensuring that you are you. DRM is about limiting what you can do with your own system in various ways and / or spying on you (even when it already knows that you are you). Simply because DRM is preemptive policing.
I have no problem with authentication, same way I have no problems with you using a lock on your door (normal security). I have problems with DRM, same way I'd have problems with police putting their camera in someone's house (overreaching preemptive policing).
Hopefully this makes it more clear. I often see people confuse DRM with merely security / authentication / encryption etc. That's plain wrong.
> The key is to realize that DRM as practiced by corporations is evil and unworkable because the economics were utterly unrealistic.
No. It's evil because it's using police state methodology of treating everyone as potential criminal and employing presumption of guilt, which results in overreaching policing measures which violate one's privacy and security.