Not supporting it would be bad for Firefox OS. It would mean that platform is locked out from streaming video solutions (ie. Netflix). This would discourage carriers from supporting Firefox OS. On desktop it doesn't matter so much. They have a marketshare to make a difference when they take a stand. However now that they're in the phone market, if no carrier will take Firefox OS due to the streaming video issue then the OS is dead before it really begins.
I think you generalize the absurd US cellular carrier situation on to the world.
Most places in the world you have carriers which provides phone services, accessible by a SIM-card, and you have phones, which accepts SIM cards.
These are two entirely separate things which you choose entirely at your own bidding. You chose the carrier which provides you with a service matching your needs at a price you are willing to pay. And you use the SIM card they provide in the phone you have chosen entirely separate.
In a world like this a carrier doesn't "support" a phone. That would be like my ISP having to "support" my Dell PC, or me having to buy a PC from a limited selection offered by my ISP. It's an absurd position.
Most of the world does not work like the completely and fundamentally broken US cellphone market, and generalizing based on that is doomed to reap highly inaccurate results.
I may be generalizing incorrectly but given Mozilla's lack of comment either for or against the W3C DRM initiative I think they're not wanting to jeopardize partner arrangements by saying anything negative. Even if they have no deals requiring DRM, why turn off potential partners with statements that don't need to be made yet.
Usually they're publicly all over this sort of thing. I don't see any Mozilla people commenting in this thread about what they think either which is unusual but probably wise.
On the other hand I don't see statements from Opera either and they're usually pretty anti this sort of thing. Maybe they're both doing behind the scenes work to scuttle the DRM initiative and don't want to make it public yet.
They stopped opposing H.264 once they needed it for Firefox OS. I'd expect Mozilla to support the W3C DRM stuff as soon as someone makes Netflix a requirement for their Firefox OS phone. Maybe it won't be Mozilla but someone shipping Firefox OS will do the work. Then Mozilla will feel pressure to take the patch they provide. They're in a difficult position now that they're in the mobile phone OS market.
Or the very real possibility that Netflix (etc.) won't even be on the Firefox OS platform without EME.
Since Firefox OS builds on an Android userland there could be overlap in the hardware-mediated playback of protected content with Android devices based on the same SOC.
To be clear, after reading the EME spec it's primary a vehicle for transmitting the state of third-party module to Javascript, that module being permitted access to the media element backing a video or audio tag and to perform the final rendering of the content to an output device.
Those who are saying this spec precludes open implementations of a user agent (web browser) should probably read the spec. Some CDM vendors will restrict their plugin from working on open browsers, but there is no reason to do that as the CDM can be the unit processing the protected stream and rendering it. This means that open browsers can implement this spec and use CDMs that conform to an open ABI without compromising the protection of the content.
The CDM if used this way will be responsible for rendering a video or audio stream, not a shared graphics context like Flash or Java, and overlay graphics and UI will be implemented in standard HTML not in the closed CDM module.
