No "however". The W3C is not actually a standards body. They don't get to tell people what to do. The W3C even knows this, even though we all colloquially call these things "standards", they're actually just "Recommendations".
The FCC is a standards body. NIST is a standards body. You go against them, you get fined. Messing with weights and measures is one of two crimes defined in the US Constitution, they both come with the death penalty, and the other one is treason.
That's not the W3C. You go against the W3C, worst case scenario, Apple says, "nah, we ain't gonna do that" and then Web devs don't adopt your feature because they can't run it on one of the biggest platforms: Safari on iOS, the only browser allowed to run on iOS.
What you've just pointed out is the W3C explicitly saying it doesn't mind if browser vendors implement features early. They "MAY" do it. And then they remind everyone the risk is on the vendor if the eventual sta... excuse me, "recommendation", diverges from what does eventually get standardized.
