What is the point of a locked bootloader if a deep flash cable can bypass it? I was reading about how important is locked bootloaders for users security after Xiaomi decided to lock some bootloaders of its phones. 1

However, I found that there is a specially engineered cable that can bypass locked bootloaders and flash other ROMs into the phone. 2

What is the point then of having a locked bootloader, if anyone can get this so called "deep flash cable" and bypass the locking restriction?
Qualcomm 9008 mode is for emergency repairs as a last resort - without it your phone could remain bricked under certain situations.

However, in case of Xiaomi phones, even if you flashed the phone under this mode, the account lock (if there is any) will still be persistent and you won't be able to use any services related to it (i.e. Cloud). The original user will also still be able to lock the phone based on the IMEI.

Additionally, Xiaomi is well aware of the security risk, and a recent MIUI8 update has patched this (Chinese sources, can't cite), putting an end to the loophole people are using.