I could forgive it if their stance was simply, "this is unfortunate but there is nothing we can do about it". But that wasn't their stance. Tim Berners-Lee (you know, the director of the W3C) was publicly endorsing DRM.
You're right that the W3C has no actual power to dictate what gets standardised anymore; they squandered that, so now only WHATWG's word matters in the end. The only power the W3C has is their ability to influence public opinion, their voice is still rather meaningful in the public debate. They could've used that voice for good, taking the side of the EFF and other pro-freedom organisations to denounce DRM. In the end, they would have had to begrudgingly accept WHATWG's DRM standard if it came to that, but they could've made it clear along the way that it's a terrible idea. This would've put them squarely in the pro-open-web camp, and would've made it clear to the public that the WHATWG is in the anti-open-web camp.
Or they could've stayed out of the discussion, accepted their irrelevance, and just adopted the W3C spec.
But they chose to actively enter the public debate around DRM in favour of this user-hostile, anti-open-web standard. They chose to use their influence to convince people that DRM is a good thing. They're on the record as being in favour of a web where it is impossible to make a proper open-source web browser which can render any standard web page.
In my book, the W3C's stance is clear as day: they're actively hostile to an open web, and they're prepared to spend any influence they might have to fight against it.