Those examples are the demonstration of my point! You had a mostly fixed standard that a small team could hope to reach - the W3C stuff - and the few top browse

Those examples are the demonstration of my point! You had a mostly fixed standard that a small team could hope to reach - the W3C stuff - and the few top browser vendors decided to extend that with a continuous stream of new features chosen only by them - the WHATWG -, with the result that browsers who couldn't keep up got extinguished from the market. That the features aren't proprietary is besides the point: Google realizes that they don't need them to be proprietary, what matters is that others can't easily implement them all.