It's a technical demonstration of the W3C WebAudio API. By your logic we shouldn't have great demos such as these because a subset of vendors haven't pulled their finger's out of their collective arses to implement a spec that's been around for a couple years.
Sorry you're pissed off, but your rant is directed at the wrong people. Go file bug reports with Mozilla and Microsoft instead of chastising someone for making something cool.
That's a little unfair. The spec was presented when it was already implemented in the browser by the spec authors. That's why they are so far ahead of the curve. Mozilla had a spec and implementation of another approach that predates the Web Audio API. Once the working group settled on what spec to go for then implementation started.
I don't like the comparison, because IE6 wasn't really ahead of its competition, yet WebKit simply gives you possibility to play with new APIs and not-yet-finished "standards", without waiting for them to become official standards (and already existing implementation helps to improve/fix them before getting final version).
I haven't checked that this is the case (i.e. whether making it work in Fx would be huge burden or even impossible), possibly not. Anyway, just saying.
EDIT: And to be precise, XMLHttpRequest is Mozilla's naming that came later (after Microsoft's interface name: IXMLHTTPRequest). So you meant: ActiveXObject("Microsoft.XMLHTTP")
Sorry you're pissed off, but your rant is directed at the wrong people. Go file bug reports with Mozilla and Microsoft instead of chastising someone for making something cool.