the really important part of html5 at the end of the day is for CONSUMER, not developers.
Here Apple doing exactly what dumb people did when they started the browsers war 10 years ago "this site is best viewed with X", which later degenerated to "if you don't have browser X, go f*ck off" (you know wars ... people pick a side).
A browser is not here to guarantee an experience, it's here to guarantee you to browse content, and wether this browser support whatever version of HTML, this browser should not be blocked in any arbitrary way because the HTML should gracefully degrade, yeah even with Lynx on a command line.
http://www.anybrowser.org/campaign/abfaq.html
that's what people don't get about HTML5 and the article make a good illustration of it.
I'm sorry, how is that supporting standard again? I'm not illuminated yet.
On the consumer accessible page Apple are requiring Safari because they can guarantee that the demos will work and they can guarantee they will have reasonable performance. And that's what's important. That's an advocacy page, a PR thing, not "look at this cool code we wrote". Presentation is everything.
In other words, different goals - different implementations.