They're going to have to create ways to play their media on Linux, with the growing popularity of the OS for appliances such as living room video players and products like the Steam Machine.
Say the W3C decided to add a new tag to HTML, called '<happy>', that displays a smiling face. Anyone who wishes (Firefox, Mozilla, you, me) could implement that feature and start properly displaying content that contains <happy> tags.
This is not true of encrypted content that requires a proprietary, closed-source CDM and / or a secret key to operate.
That is why EME should be rejected by the W3C. Lack of Linux support is a consequence of the problem, not the problem itself.
The spec says "The Content Decryption Module (CDM) is a generic term for a part of or add-on to the user agent that provides functionality for one or more Key Systems."
What, you were talking about GNU/Linux? See, that is not going to happen. Instead, you'll see the Linux kernel, some GPLv2 userspace, and a hardware-enforced lockdown that renders the GPL useless. There will be jailbreaks but only a minority of people will even be aware of them, let alone care enough to actually make use of then.
Wouldn't it be more logical to say something like, for the first time in the history of the W3C, the W3C publishes a non-Open Web spec? Or something like that.