rfaUnlocking the bootloader allows the user to change the kernel, and certain kernel changes can cause permanent hardware damage, some examples of common custom kernel changes:
Isn't the warranty on the hardware? How does altering the software affect the hardware?
mosimchahCorrect mosimchah, that is why rooting the device voids the software and hardware warranty. We can only guarantee the hardware to run in specification if it has always been running in specification.
Unlocking the bootloader allows the user to change the kernel, and certain kernel changes can cause permanent hardware damage, some examples of common custom kernel changes:
CPU/GPU overclocking can shorten the lifespan of the CPU/GPU
Relaxing the thermal restraints in the kernel can cause parts of the phone to overheat which can cause damage
Undervolting/overvolting different components can cause issues
Increasing the charge rate can damage the device
Increasing the display hz might cause some issues although I'm not entirely certain about that
And there's a lot more, the kernel handles a lot of things, it would not be at all reasonable to ask Asus to cover hardware damage that might have been caused by a custom kernel, not to mention that even without touching the kernel you can use simple root access to change the thermal throttling restrictions in the vendor partition which can completely fry the device, this is a common practice by some power users in order to get better performance in games