[bzbarsky]

Webkit has no problems providing an experience that the IE team thinks is subpar (in particular, lacks full 2d graphics acceleration).

Similar for Gecko: it's doing compositing acceleration on WinXP, but not 2d acceleration.

Now maybe the argument is that IE9 should support such a mode of operation. But by the same argument, Firefox should still have a supported PPC version of Firefox 4 (even though it's JIT can't generate PPC code, so JS would be interpreted and hence very slow). Some people _are_ making that argument, by the way, but the general consensus is that this sort of decision about what sort of quality they're willing to put their name on is up to the Mozilla project. Why does the IE team not get the same courtesy?

I realize that you may disagree with their quality metrics (e.g. you may think that a modern JS JIT is a must-have requirement for a modern web browser but 2d graphics acceleration is not). But it's not clear to me that this is obvious, or that this will even be true in a year.