the problem with this argument is that any manufacturer can be preinstalling spyware in the future and you won't know until it becomes public. Lenovo did but apparently stopped after it got caught. My point is that all OEM's are on the same boat.
So even if you want to install MS Windows from official microsoft media, you can't.
Why would lenovo would disable AHCI (which breaks windows and linux), then mess with a fake RAID (despite having a single storage device).
Seems like Lenovo REALLY doesn't want consumers reinstalling the OS.... makes one wonder.