Two years ago, flash was the only game in town; Good HTML5 implementations were no where to be found, and Silverlight adoption was a joke. It's not like you could HTML5 an equivalent to flash on an iPhone OS 3.
I agree that things started changing rapidly two years ago, with the introduction of iOS 4. But there was never a stalemate -- Flash was king; then there was chaos; and now HTML5 is winning (for the time being, though not for long, Flash is still among the royalty). Silverlight had always been a wannabe.