The most likely reason is a stripped down version of periphal support, no new feature releases etc. It's more of set and forget installations rather than a daily driver.
2 reasons - a lot of endusers appreciate it surprisingly, and some of those bloat of preinstalled applications subsidizes the cost to make it cheaper to purchase.
Then they wouldn't want to disable it; what harm is there in offering the choice?
But you can disable and remove it - manually. These scripts do it automatically for you as a convenience but the ability is there.
In enterprise versions of Windows, there's tighter control and less "features"/bloatware installed by default, and you can use GPOs and other settings to deal with it very easily. This of course comes at a cost that most endusers don't want to pay.
Feel free to purchase the non home versions of Windows and you will find there _is_ a choice.
I have spent a lot of time on three platforms, including multiple Linux desktop managers, but have not seen anything better than the window management in Windows 11. (I am aware that this article talks about Windows 10)