I clearly wrote "the very first sentence of that rationale section". Even though you've erroneously picked the standard from 2004 instead of the current edition, and then erroneously didn't even look at the rationale, the first sentence of that section of that old edition's rationale is the same.
"This chapter contains the definition of the Shell Command Language."
I'm not familiar with the advocacy. I'm not sure that I would see much value to it.
https://pubs.opengroup.org/onlinepubs/009695399/utilities/xc...