Here the unbrick state means the device is stuck at boot logo or stuck in bootloop. Not just during modification, this can happen while updating the phone manually. But if you are modifying your device for the first time then there are chances that you may brick your phone. It doesn’t even take a month after release to receive work from custom developers.
And it doesn’t let you down as unlocking bootloader, rooting and another modification is much easier than other phones. Most of the users opt Xiaomi’s phone because they like to try custom ROMs, custom Recoveries on their phones.