Apple jumped onto the split-core train early on, because it was the first having access to more advanced manufacturing processes.
CPUs with big and little cores were not useful for the old "14 nm" manufacturing processes used by Intel for Skylake and its derivatives, because in those processes the power consumption of a core and its speed could be varied in a very large range, e.g. for the extremes of the supply voltage, the clock frequency of a laptop CPU core could vary between 0.6 GHz and 4.5 GHz, corresponding to a variation of the power consumption per core of even 50 times.
Modern processes have more constrained ranges for the optimal operating parameters of the transistors, so it has become better to split the cores into several classes that are designed with different trade-offs between power consumption and performance, instead of attempting to use the same core both at very low and at very high power consumptions.
The decision to use 2 or more kinds of cores to cover the entire curve of performance vs. power consumption, when you can no longer cover it by varying the operating parameters of a single kind of core, is a no-brainer.
While for the CPUs with a small number of cores, like for smartphones, tablets and light laptops, the existence of multiple kinds of cores is needed for optimum energy efficiency, the CPUs for desktops or big laptops with a great number of medium-size cores, like Raptor Lake, have them for a different reason. The big Intel cores, in the quest for maximum single-thread performance, have poor performance per chip area. The medium-size cores have better performance per area, so in the same limited chip area you can put more cores, increasing the multi-threaded performance beyond what would be obtained by filling the same area with big cores.
Nevertheless, AMD has a better strategy than Intel, because their big cores with high single-thread performance and their "compact" cores with better performance per chip area are logically equivalent, avoiding the software incompatibility problems caused by Intel.
CPUs with big and little cores were not useful for the old "14 nm" manufacturing processes used by Intel for Skylake and its derivatives, because in those processes the power consumption of a core and its speed could be varied in a very large range, e.g. for the extremes of the supply voltage, the clock frequency of a laptop CPU core could vary between 0.6 GHz and 4.5 GHz, corresponding to a variation of the power consumption per core of even 50 times.
Modern processes have more constrained ranges for the optimal operating parameters of the transistors, so it has become better to split the cores into several classes that are designed with different trade-offs between power consumption and performance, instead of attempting to use the same core both at very low and at very high power consumptions.
The decision to use 2 or more kinds of cores to cover the entire curve of performance vs. power consumption, when you can no longer cover it by varying the operating parameters of a single kind of core, is a no-brainer.
While for the CPUs with a small number of cores, like for smartphones, tablets and light laptops, the existence of multiple kinds of cores is needed for optimum energy efficiency, the CPUs for desktops or big laptops with a great number of medium-size cores, like Raptor Lake, have them for a different reason. The big Intel cores, in the quest for maximum single-thread performance, have poor performance per chip area. The medium-size cores have better performance per area, so in the same limited chip area you can put more cores, increasing the multi-threaded performance beyond what would be obtained by filling the same area with big cores.
Nevertheless, AMD has a better strategy than Intel, because their big cores with high single-thread performance and their "compact" cores with better performance per chip area are logically equivalent, avoiding the software incompatibility problems caused by Intel.