If "standards compliant" means implementing every feature then no new (or existing) browser will ever be standards complaint anyways. This is not a lever that can be used to force everyone to implement DRM.
If only a select few can implement it, then why call it a standard?
The standard (that is being proposed) in this case is an interface that the actual DRM modules hook into. Anyone can implement the interface.
In this case, the implementation of the DRM hooks are those proprietary DRM modules.
This "standard" shuts everyone except the select few in the dark. Without have the appropriate plug-in, you cannot access the content.