That the W3C wasn't a useful bastion against DRM is an understatement. It was the main driving force. WHATWG, on the other hand, appears to have opposed it.
A few tech companies have outrageous _corporate_ influence in the W3C who shouldn't.
To name a few: Google, Microsoft, Netflix.
I predicted serious issues with this ages ago, to the point that I suggested the best thing for humankind would be a fork of the HTML spec on behest of WHATWG. I also remember some long time independent contributors like Anne van Kesteren agreeing to this at the time.
https://blog.whatwg.org/drm-and-web-security
So what purpose did the W3C serve? Transforming user agents into entertainment industry agents, I guess.