Yeah this is probably correct. Still, on some rare occasions it's so hard to get into a topic that if there's a good book I would give it a try. For example: I'm interested in Ruby internals. The codebase is very very complicated and I have no background in interpreters; in that case Ruby Under a Microscope is a life safer. I would say the same if I was looking to get into Linux kernel development.

But in general - if you are just trying to become a better software developer (e.g write clean, well tested code) you are absolutely right no book will get you there, hard work will.