PXE, or network boot. It is basically never used (and rarely enabled, if ever, by default) by the individual, but can be helpful in, for example, a large scale OS deployment. Say IT has to get their corporate image version of Windows 10/11 installed on 30 new laptops. They could write a ton of flash drives, but it'd be easier to just host a PXE boot server and every laptop just listen to them.
V6 specifically in that instance would just be for the reason of "we need to move away from v4 anyways"
Running xfce4 Fedora brilliantly on an old Dell Chromebook thanks to this, fully recommended!!