Apple not supporting Flash was a crucial part of it's demise, though. Without that, we might be running Flash on mobile today, even though it was terrible.
They did actually support it for a while on Android, but Apple never wanted to support third party browser plugins on iOS, and since the Android port was horribly slow even on the most basic swfs and was a huge hack, Adobe decided to drop it. AIR is still supported on both platforms, though (and I hear it's quite good).
Flash wasn't even supported on iOS. I'd argue that was huge in killing off Flash, since anybody who wanted to make their site work on mobile could no longer use Flash.