It works for them because they own the complete hardware stack, and boot only their hypervisor which is also something they control. TL;DR you can make it simp

It works for them because they own the complete hardware stack, and boot only their hypervisor which is also something they control. TL;DR you can make it simple if you close the platform (this is not the same as open source Vs closed source) - open platforms end up developing complex interfaces so thatthey are actually open to end owners.