I think it's more practical for browser vendors to develop ideas (in the open, not like Dash) and use vendor prefixes (-o, -moz, etc.) and then bring those ideas to the standards bodies. We've seen this a lot recently, particularly with mobile. meta viewport tag was not brought to standards bodies first, Apple developed it and everyone else adopted it. To my knowledge it's still not part of WHATWG, although I'm sure it eventually will be.