16 bit is really a hackfest and 16 bit machines are really too slow to be useful as a general purpose computer and not supporting them to save a lot of development time and avoid nasty hacks was a design decision.
GCC does support outputting 16 bit code for 16 bit microcontrollers as a single program - which is what those kind of computers are good for.
@lucy `If people pressure you to make your program run on Windows, and you are not interested, you can respond with, “Switch to GNU/Linux — your freedom depends on it.”` - banger.