It's no more misleading than saying it runs on bare metal. If I flash the correct motherboard ROM chip with the necessary bits to play Tetris in the UEFI (or completely replace it), would I be running closer or farther from "bare metal" than this is? Am I still on bare metal if I choose to use GRUB for loading up the game? Do I become an OS if I use GRUB instead of embedding that logic within my binary?

We call things BIOS and Boot-loader and Operating System by virtue of history, not necessity. It could even be confusing to a newcomer looking into development closer to the hardware and being told that all these programs are fundamentally different, instead of just being instructions and data getting shoved through a bunch of tubes in the processor and PCB.