I totally agree that cross-platform app frameworks never become de facto standards, because adding an extra layer of abstraction between native UI widget APIs u

I totally agree that cross-platform app frameworks never become de facto standards, because adding an extra layer of abstraction between native UI widget APIs usually dumbs down the user experience. However, cross-platform frameworks that don't try to replicate platform's native UI experience, have been and are successful, mainly in games. And Flash can be seen as a one and by far the most succesful contender in that space. After HTML/JS that's it.