It's not so simple. Content providers want to distribute on the web. Yes, they have the ability to just pull out and avoid that space entirely, but that's not good for them. The web needs their content, but they also need the web.
In other words, the W3C saying no to DRM would apply pressure in the right direction.
That suggests positions can be shifted. And we have seen them shift before, with music downloads, which used to be DRM'ed, but no longer are.
That is a sign they were losing the battle, and they absolutely were with the rise of youtube, facebook video, twitch, etc - alternative video sources were / are starting to get professional, with many major youtube channels having production crew and proper film / showmaking.
The web would have been absolutely fine without them, but they knew they would not survive without the web long term, especially internationally.
EME is enabling black box plugins, simply calling them "extensions" does not magically make them something other than a Black Box binary blobs loaded by the browser.
Functionally they are really no different than the Flash or Silverlight plugin, they simply contain less stuff and are more specialized
W3C is suppose to be promoting the Open Web, that means open regardless of Operating System, Browser Choice, or Nation
EME violates all 3 of those by locking you down to only commercial, or commercially supported browsers (no open source EME, even Mozilla had to pay Adobe to create them a Commercial non-free plugin for FF)
Free/Libre Operating Systems are Excluded from the new w3c vision of the web
EME/DRM enables Geo-fencing of content
In short the EME is a complete bastardization of the w3c mission
The only influence W3C has on DRM is the form it takes: is it implemented through (somewhat) standardized means, using the building blocks of web technology provided by browser vendors, or is it implemented through black-box plugins that we know, after 15+ years of experience, end-users will install.
I have never really understand the role W3C is supposed to play as a pressure point for DRM.