Abobe's failure to switch the flash tools to targeting HTML5 is one of the most inexplicable decisions of all time.
In late 2000s they owned the Web App space ( what was called Rich Internet Applications in their speak). Flex (their business GUI components library and markup language) was absolutely dominating corporate Web app development.
And they just abandoned it.
In an alternative reality we are all building HTML5 Web apps with Flex Builder right now.