I categorize this as one of the better points of the book.
functions should do one thing
I kinda disagree with him on this point. I wouldn’t necessarily limit to one thing, but I think functions should preferably be minimal.
Throughout his examples he’s also using ideas like how functions should only be 3 lines long, preferably have no arguments, and also no return values.
This style of coding leads to programs that are nightmarish to work with. The relevant code you’re looking for might be 10 layers deep of function calls, but you don’t know where. You’re just jumping between functions that does barely nothing until you find the thing you’re looking for, and then you need to figure out how everything is connected together.
I prefer when things are flatter. This generally leads to more maintainable code as it’s immediately obvious what the code is doing and how everything is connected.
I think his book is the equivalent of a cleaning guide where all the steps are just to sweep all the mess under the carpet. It looks cleaner, but it’s not clean.