Agreed, canvas works well now, but WebGL is younger than canvas, and this gives a hint at what WebGL will look like tomorrow.
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