Well, one reason you'd need one is if your boot filesystem is encrypted and you want to be able to reboot the machine remotely. (I use ZFSBootMenu for this purp

Well, one reason you'd need one is if your boot filesystem is encrypted and you want to be able to reboot the machine remotely. (I use ZFSBootMenu for this purpose; it's accessible via SSH and can be used to decrypt the filesystem and choose what to boot.) There are hardware solutions to that problem, but most regular PCs don't come with a remotely-accessible boot menu.