I think that's a bit backwards. Flash provided a solidly mediocre experience. Non-native widgets (and consequently input issues and accessibility issues), high cpu usage and generally poor performance for things like video playback, poor security track record… on desktops. Avoid that on a more constrained platform was a no brainer.

Adobe's inability (or unwillingness?) to come up with a competitive product killed Flash. Jobs' unwillingness to hitch his wagon to Flash was a symptom not a cause.