I'm fairly sure it's to do with lots of developers being scared to write even basic client-side code without loading and calling a bunch of random functions on

I'm fairly sure it's to do with lots of developers being scared to write even basic client-side code without loading and calling a bunch of random functions on an 8mb framework. Sadly rather than treating user processors as a sensible saving of server time, developers have been treating it as an all-you-can processing buffet, taking more and more cycles without even bothering to think of a good reason why.