It's worth pointing out that there are a ton of frameworks and libs for propriety development environments too. Even where there is a dominant framework you the

It's worth pointing out that there are a ton of frameworks and libs for propriety development environments too. Even where there is a dominant framework you then get micro architectures on top of that. With the web as an application development platform it's still very young and there is yet to be a defacto standard for a few years. Until then frameworks will come and go. jQuery for example more or less won out against dojo or prototype (and I expect 100's of others that were less popular). The democracy that drives the web forward is a double edged sword. While the Android, iOS SDKs are great now, they may well be dead in a few years, whilst the web will still be here. Just ask Swing, JavaFX, J2ME, Enyo, Symbian, Flash or Silverlight developers ;)