The fact that Windows tries valiantly to offer backwards compatibility (actually is forced to by their own business model) I have to assume is at least partial

The fact that Windows tries valiantly to offer backwards compatibility (actually is forced to by their own business model) I have to assume is at least partially responsible for the overall huge suckage that is working on Windows. OSX/iOS are much more like Ubuntu -- practically any cutting-edge app requires something near to the latest OS release. Android is suffering precisely because there is low OS upgrade adoption, as I've heard recently right here on HN.