Seeing how buggy and slow Flash is only on OS X it really is "can't".
What happened to Adobe fixing that? Hasn't it happened yet? The Windows one is better than ever-the current version even has GPU accelerated video playback on Nvidia GPUs, with non-video GPU acceleration coming later.
I know back maybe 8 years ago I'd have stability issues with anything fancy on OS X. Ironically couldn't play this really funny OS X comic on OS X.
Of course that was long before Adobe bought Macromedia too, so between that and Adobe talking about bringing about parity I'd think it would be better by now (?)