Flash was never going to gain ubiquity on mobile devices, thanks to the fact that Apple resolutely refused to adopt the technology on the iPhone or iPad. "No matter what we did, the Flash Player was not going to be available on Apple’s iOS anytime in the foreseeable future," he says.
Meanwhile, HTML5 is ubiquitous. "On mobile devices, HTML5 provides a similar level of ubiquity that the Flash Player provides on the desktop," Chambers says.
Users don't consume content on mobile in the same way they do on desktop. Differences in screen sizes, latency from wireless networks and the ubiquity of app stores made Flash less relevant on handheld devices.
Developing browser plugins for mobile is much more challenging than the desktop. It requires more partnerships with OS developers, mobile hardware manufacturers and component manufacturers. "Developing the Flash Player for mobile browsers has proven to require much more resources than we anticipated," Chambers admits.
Adobe wanted to shift more resources to HTML5, and dropping Flash for mobile frees them to do so.