That's the thing I don't really understand. They know this policy isn't stopping anyone, only upsetting the legitimate users that do want to unlock the bootloader, yet they keep insisting on it.

Or maybe the real reason is a little less rosier... Xiaomi paints themselves (to investors) as a software company, not as a primarily hardware manufacturer. It's hard to be a successful software company if (most western) people only really want the hardware, but ditch the software as soon as the phone gets in their hands.

My only real complaint is that they should be more transparent (even honest) about this to the average joe. Don't like it, don't buy it.