I don't get this site. Yes, emacs can be used to read/write files, and yes indeed if you set the SUID bit or run it via sudo it'll have root privileges... And?

I don't get this site. Yes, emacs can be used to read/write files, and yes indeed if you set the SUID bit or run it via sudo it'll have root privileges... And? Is this a common configuration on some system I'm not aware of? What does any of this have to do with LD_PRELOAD?