Why bother use a GPT-3 model when you can use the free BLOOM model? Large "foundation" models will become a commodity -- a race to the bottom.
In my small amount of testing of Bloom so far it seems capable of advanced behaviour but it can indeed be trickier to coax that out. Playing with temperature and sampling matters for sure.
But for the moment you can't just use pure natural language instructions with BLOOM indeed. Maybe it will come!