Content Question: Business Analyst Training Lesson 3. SIPOC purpose?

https://academy.uipath.com/learn/course/386/play/2659/lesson-3

For the Business Analyst Training Lesson 3 the focus is on creating documentation.
It is mentioned that for step #2 we do process mapping.
It’s unclear to me why we should consider using SIPOC if step #2 focuses on high-level process mapping.
Is SIPOC more of a segue into step #6 for L4 Level Process Mapping?
(also it seems to skip step #4).

If anyone has any ideas please let me know.