While “single level of abstraction” and “doing just one thing” are correlated, they are still different concepts.
Furthermore, “single level of abstraction” is not substitution for “short functions”. It is possible to write (undesirable) 50+ LOC functions at a single level of abstraction. Therefore, this statement is controversial at best:
So the question is not how long a function is, it’s what is the level of abstraction of a function
These are really two independent questions that must be asked.
The title suggested that this article discusses SLAP, but this principle was barely mentioned, and was immediately (and, IMHO, erroneously) substituted with completely different one.