I do, then I worked on single page apps with dozens if not hundreds of screens, dozens of developers, and tens of thousands of lines of code; modern Javascript standards and new transpile-to-javascript languages that all had to work down to IE 9; front-end application frameworks and 3rd party libraries that helped us to structure the application and not reinvent the wheel without having to manually sift through all files at every release (thrice or more a day) to filter out what we needed.

Uploading some files is fine for simple websites with no availability guarantees or security requirements. Mod_pagespeed is fine for most websites too, I should install it for my wordpress instance sometime. It's not effective for single page apps though.