Nah this kind of thing is pretty common for servers or little embedded computers. If you're always building the image on some other machine, there's no compelling reason to include that binary or it's dependency closure on the system.

Typically someone who goes for this indeed likes and runs "full fat" NixOS on some systems. What they want is to get really small images for some special purpose, like containers or disk images for a puny old Raspberry Pi, and build them using their usual NixOS workstation or server or whatever.