Slightly off topic, but what's funny is that I only realized last year that
UEFI basically is the new DOS! I had a system where I was forced to do some things in the UEFI shell, and when I started looking into it, I came to see that it's really very DOS-like.
You can write your own programs for UEFI, as well. It does seem like a somewhat better-featured version of DOS, where you get basic services like hardware abstraction and a network stack.
If I needed to use a PC for something where I had virtually exclusive control over the CPU (e.g. some sort of simple, realtime control), I might be tempted to explore running it in UEFI.