It is both funny and sad that in these days of the "open" web it is actually much, much more difficult to get good cross platform results when doing anything with graphics/sound.
What's more today the first cause of WebGL not working lies more in the graphics card periphery. OpenGL drivers on Windows are often an aftertought given DirectX prevalence, and on Linux some drivers are simply unstable with 3D acceleration, regardless of WebGL. Besides, short of software fallbacks like llvm-pipe or OSX, you can't invent features not supported by the card. Onve overriden[2] WebGL actually works[0][1] well on my embedded HD2000, but bugs in the driver make the whole thing randomly unstable, hence it is blacklisted by browsers (chrome://gpu even lists and links to bug reports, and lists Flash Stage3D as blacklisted too).
As for number counting, while the number of people running into WebGL problems exists, it has been drastically reduced since a year ago, when the number of people running into Flash problems for years, and is not shrinking.
ALso, there's not just graphics on X-Type, but correctly timed HTML5 audio too.
[0]: http://madebyevan.com/webgl-water/
[1]: http://alteredqualia.com/three/examples/webgl_cars.html
[2]: "Override software rendering list" in chrome://flags
The story with Flash was much more single-vendor-dependent despite the half-hearted noises Adobe made over the years about supporting alternative implementations.
That said, I've started playing with Three.js lately and it's impressively straight forward and filled with capability.
These days I do Objective C, but I still love AS3 & the Flash API. I just wish browsers would implement it natively (a JS version of the API), as opposed to the HTML canvas and (currently) flaky support for audio.
Actionscript 3 was such an enjoyable language to code in, though I haven't been able to use it professionally in over a year due to demand; the extent of my 'interactive' work has been hacky, ill-performing CSS3 transforms, and WOW are they limited.
It's been all JavaScript, all the time, and I do love the community but then again I really (really) miss the rich immersive creativity that used to be so inspiring on the web.