You are right, but in the context of CPU cores the normal criteria for optimization are the ratio between performance and energy consumption and the ratio between performance and price, where the price is supposed to be determined by the manufacturing cost, which in turn for a given manufacturing process is determined by die area, so the second ratio becomes the ratio between performance and die area.

If economic criteria like money spent for the design are used for optimization, than it becomes pretty much impossible to compare the competing companies, because almost every CPU design might be considered to have an optimum IPC, no matter how bad it is, because it is the best that could be achieved within their budget, by their design team.

Because Apple can sell expensive products, the die area and the cost of the manufacturing process had little importance for them. Because their products use only few cores, the area of one core was not constrained, because the total die area remained below the process limits, when the core area is multiplied by the number of cores.

So their main optimization criterion has been the ratio between performance and energy consumption for a single core, without area per core and power dissipation per core constraints. In this case the IPC is not constrained, there is no optimization problem for determining the IPC, the higher IPC, the better. Therefore, unlike the designer of cores for a server CPU, Apple has designed the cores with the highest IPC that they could achieve within the project schedule and budget, in a given TSMC process.