I don't think the issue is about which code is more readable, but whether it's efficient for the CPU or the computer. Modern compilers optimize more than we think in production builds.
I don't think the fact that a function works well is a good enough reason to write a 2000 line function. Sometimes there are long pieces of code that implement complex algorithms that are difficult to break into smaller pieces of code, but those cases are limited to the few you mentioned.
Mixing different levels of abstraction makes the code harder to understand. Linear code is probably good because the examples in the body are simple. It's one thing to separate code into separate files, but it's another to break up code snippets in one file.