The big problem is copyright on all the specs is owned by the W3C. Oh, you want to spec CSS? Well, then you have to do it from scratch. Yes, HTML is now at a point where it is better specified than ever, and more interoperable than ever, but it's been a long, hard journey there. Consider the spec has been worked on for over a decade now. Respecifying, from scratch, large parts of the web platform is an incredibly large undertaking, especially ensuring the spec defines something compatible with almost all web content when browsers frequently disagree in edge-cases with up-until-now unspecified behaviour.
Oddly enough, the people producing those three browsers just happen to all be DRM system vendors (WideVine, FairPlay, and PlayReady). Who would think they're want to build their own DRM systems into their browsers, eh?
Perhaps you're thinking of something like the WHATWG? (bad news for you on the Google front if it is)