The reason is the platform vendors (Apple and Google, mostly) are doing a really poor job implementing modern HTML features into their browsers. The browsers,

The reason is the platform vendors (Apple and Google, mostly) are doing a really poor job implementing modern HTML features into their browsers. The browsers, while continually getting better, and still far behind desktop. I'm not just talking about in performance, but in feature parity. I'm not sure why Google is having such a problem speeding up their development of the Android browser, as they have no trouble on the desktop. I suspect that the Android browser is made within the Android team and not within the Chrome team, which is a problem. I'm also worried that because the browser is such a central part of the mobile experience (appearing in the doc, being opened from within any app), it makes it VERY difficult for competitors to gain a market, much more so than on desktop. Add to this that Apple doesn't allow competing layout engines and I'm worried that the mobile browser might never get to the point where the desktop browser is today.