Comment by IshKebab

It's useful for shared spaces like schools, universities and internet cafes. The point is that without it you can display a fake login screen and gather people's passwords.

I actually wrote a fake version of RMNet login when I was in school (before Windows added ctrl-alt-del to login).

https://www.rmusergroup.net/rm-networks/

I got the teacher's password and then got scared and deleted all trace of it.