As opposed to the large portion of comments, I don’t think that the author is suggesting 200 lines of functions.
I am seeing examples of code that is trying to reduce the number of lines from 10 to 7 by extracting a function that does not contribute to readability, and increase complexity and brittleness of tests by adding a mock to the existing tests and move test cases to a new file so that new small function can be tested in isolation.

I’ve also seen a lot of examples of prematurely optimized (for the length) functions which just increases integration points on the single task that creates more brittle tests by increased use of mocks.

Over all, short functions are good things but as with every vague description, “short” is a highly subjective word. Combined together with blind adherence to “best practices” it can easily get out of hand. That’s why philosophy is more important than the best practices