Why does OEM versions of Windows even exist in the first place? How is a bloated, crapwared system ever going to be a better user experience than a clean install?
But the answer to the question "Why do OEM versions of Windows even exist in the first place" is that without OEM customization, a Windows computer is a non-functional computer.
I even worked at a few places that created their own UNIX flavors (mostly GNU/Linux based).
Of course you can build SOEs with manually assembled sideloaded drivers, especially if your organization uses just a handful of different models.
I have reinstalled Windows on quite a few laptops and desktops and have been quite surprised with how much works straight out of the box these days (mostly everything in my experience, bar some stuff like Fn keys). YMMV of course.