I’m not at all convinced. The pictures I’ve seen of the CPUs that implement this kind of technology show that even if you split them into equal numbers of CPU

I’m not at all convinced. The pictures I’ve seen of the CPUs that implement this kind of technology show that even if you split them into equal numbers of CPU types, the little ones take up way less space, approximately 4x less. So, in the space of 5 “BIG” cores, you could instead get 4 “BIG” cores and 4 “little” cores. This seems like a huge win to me, since each of those little CPUs could do a lot of background tasks that always need to be done, but don’t need to take up a full “BIG” core to execute. You get a lot more parallelism this way, for relatively little cost. That seems to me to be a “BIG” win.