I don’t think that’s the point, when you get a device from Aliexpress that’s been tampered by the retailer (as opposed to the OEM), the bootloader will already be unlocked and you could install a clean OS. That’s okay if you are the one buying the device and somehow trust that the retailer hasn’t messed with the hardware as well, but it doesn’t help the manufacturer that wants to stop retailers from messing with the OS in the first place.