How many apps in the World require a specialised framework that GMail might require? 10? 100? 1000? Sure, everyone can invent their own framework to be very &quot;specialised&quot; and &quot;tailored&quot; to a given app needs but is it going to give a competitive advantage for a given app? Probably sometimes. Probably not most of the time.<p>Constructing your own framework has cost. Sure, you will acquire a lot of knowledge doing it, but is it going to help the bottom line? Maybe.<p>Once again, are you seriously advocating that _everyone_ should do &quot;vanilla JS&quot; without any frameworks?