It's a pentesting technique, used to assess the level of effectiveness of user training. While your final comment is accurate, it is impractical as usb mass st

It's a pentesting technique, used to assess the level of effectiveness of user training. While your final comment is accurate, it is impractical as usb mass storage is still required in many places. Also, you can't effectively block HID, and an attacker can use HID disguised as or in a thumb drive to successfully attack a network.