"And learning to code by reading a Rails book? Don't you have to know how to code before you build even a basic Rails app? Even average coders can't easily grasp all the concepts behind building a full-fledged web app, nevermind someone who barely knows what a for loop is."

Agreed. As someone who has some coding experience (i.e. current CS student) but who is learning web dev, many parts of Rails/Django are way over my head. Rails/Django weren't designed for beginners. I've found starting with Flask which does considerably less than Rails/Django to be much more understandable. Sure I am probably often reinventing a shittier wheel but I think there is benefit in understanding what a full blown framework like Rails or Django provides before using one.