Lots of work/school computer has a password locked BIOS which prevents you from booting from anything else. If they also have a physical lock on the computer, or if it's a laptop that you can't open or doesn't have a bios reset functionality, or you're worried about getting caught opening the computer, you're effectively locked out.
This exploit does actually open possibilities where there were few/none before. Also I imagine it's easier for some people to execute.