I'd say that web apps became a thing because Google really wanted them to be. They first tried with their browser plugin. That worked, but adoption wasn't good

I'd say that web apps became a thing because Google really wanted them to be. They first tried with their browser plugin. That worked, but adoption wasn't good enough. So they ditched Google Gears and started developing a browser with sufficient performance for web- native apps. They succeeded quite well. So in my view, browsers became capable, but then plenty of "heavy" web apps appeared, which required more beef in the machine. That's also the typical way it goes: current hardware being okayish but not great is one of the strongest drivers for better hardware. Whether it is gaming (PCs), camera (smartphones), the web bloating (both).