They also don't use Access to store Windows Update catalog. I don't see anything wild here, appropriate tools for different jobs.

I was responsible for a MS dynamics implementation at a public company. I would agree.

(This was also my motivation to start my own financial reporting startup: what if we designed a system in the year 2022 to be able to support big businesses without it being as awful as big business software.)

To be honest, i think that even if they offering overlaps with SAP R/3 or S/4HANA, they overlap at the lower end (500-5k employees) and not really at the top end (> 100k employees) where MS sits.

Furthermore, AFAIK Microsoft started using SAP well before they acquired Axapta.

MS uses Dynamics for a ton of internal processes, just not all of them. I suspect the SAP installation predates the existence of Dynamics as a product.

Are you a 100,000 employee company?