No, that's not my argument, as you can see from my comment above. What you've done here is twist my argument around to introduce claims I didn't make that you find easy to rebut.
> by standardizing everything but (in essence) the authenticated key derivation step
Is there another interpretation of 'everything' in this context? You're making EME far more comprehensive than it is. CDMs do way more than derive a key, so your statement is false on its face.
Your argument is that EME covers most of the code responsible implementing DRM. This is false. EME is a small part. The large majority of the implementation is not standardized. For example, there is no equivalent of NPAPI in the post-EME world; the CDM/browser interface is browser-specific.