I believe that his example for sanitizeMessage() was just to give an example. An actual sanitizer would be much more complex, and thus having a separate functi

I believe that his example for sanitizeMessage() was just to give an example. An actual sanitizer would be much more complex, and thus having a separate function defined to do that one thing would be more obviously reasonable. But you DO want these single responsibility methods like sanitizeMessage()! Having single responsibility functions like this means you have more Legos you can use where you need. You get improved code reuse. Perhaps more importantly, you also get functions which are easy to test and test more thoroughly than if you have a big procedure which does a lot of things.