That argument seems isomorphic to demanding that all software design and feature innovation happen within the W3C commitee process. Certainly that's not how most successful features have worked historically...
1) Single Browser Ideates -> Single Browser Ships -> Time Passes -> Other Browsers Ship -> Standard. This caused delay in implementation and vendor prefix hell.
2) W3C Ideates -> W3C Bikesheds -> Browsers Implement. This causes things like AppCache that work on paper, but don't adequately cover developer use cases and address the needs of the platform.
The ideal process (in my opinion)
1) Single Vendor Ideates -> W3C Evaluates/Refines -> Browsers Implement Under Feature Flags -> Standard -> Feature Flags are removed. This process, depending on the size/scope of the change, should take about 6mo to a year. For a permanent irrevocable change to a cross-browser API? That is mature and prudent.
edit: formatting.