I think the idea is that the majority of the script will be written in pure JS, with only occasional calls out to subprocesses, so “every command” is far from e

I think the idea is that the majority of the script will be written in pure JS, with only occasional calls out to subprocesses, so “every command” is far from every line. You frequently see the same mental mismatch when shell-scripters try to use Python, and complain how hard it is to pipe with POpen, instead of using the built in string processing features.