Sorry if you took my comment as the implication that version numbers don't matter; they certainly do. But the relationship between specifications and browsers is complex.. My point is only that putting version numbers (instead of timestamped commits) on a spec doesn't assist browser makers.

Specification test suites are really our greatest hope at early cross-browser compatibility and right now they're not in a great state. See also testthewebforward.org which aims to assist this (and movethewebforward.org which birthed it)