The AHCI / RAID switch the author is describing is only relevant to drive controllers which support SATA disks - AHCI is the protocol that's used to interact with a SATA controller. This switch has no effect on NVMe drives, and never has; the fact that the BIOS control for it even mentioned NVMe is odd.
The "RST storage driver" (i.e. Intel Rapid Storage Technology) is only required for systems which support SATA RAID using an Intel integrated RAID controller. It is not required to use NVMe devices. I wouldn't expect Dell to provide this driver for systems which don't use SATA disks, since it wouldn't do anything.
It certainly wouldn't surprise me if there were some weird trick required to perform a clean install of Windows on these machines. But I don't think the author has identified it correctly, and I find their theory that this is a deliberate effort to "control the user experience" unconvincing.