Is that true, or the reverse? That web apps became a feasible thing only after consumer hardware, esp phones, became performant enough to handle loads like that (which lead to less and less offloading to servers)?
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).
