The standardization of required codecs for the `<video>` element is indeed a wonderful accomplishment by the non-W3C HTML5 WHATWG.
Seriously, a third-party neutral organization will always be needed. Who will you appeal to when the main companies start having different ideas about something? Another thing that organizations like W3C or IETF do is to provide some kind of shelter from patents and similar problems.
We can discuss about the efficacy of such shelters and about the ability to mediate between different options, but the web is definitely under a better situation than wireless telephony, a field where company-run consortiums decide standards and "settle" disputes.