Gotham Knights is a good example. Two threads are taxed, rest of the CPU is asleep. Technically it’s CPU-limited, but we know it’s not because the CPU is too weak.
Exactly.... and you can look at every single other game that is "CPU limited". Each core is averaging around 15-35% utilization most times, with one or two cores averaging 90%.
That is not a CPU bottle-neck, its poorly optimized code.
And this brings us to the kinda choice these console manufacturers have to make. Sony KNOWS this, they have tools that track every minute detail of how games are run on their platform. They know that the CPU is not weak, but they also know that devs are very unlikely going to make properly optimized code to fully take advantage of it.
Which brings us to the zero-sum solution. Even if you put in a Zen 4 CPU, in a console, you have a thermal envelope of around 200W for your APU to work with. The only way that CPU makes any kind of sense, is if you are clocking it as high as say 4.5Ghz -5Ghz. Or not whats the point, if it's clocked at the same 3.5Ghz, it would perform no differently from the Zen 2 one and still be "bottlenecked". Maybe you get about a 10-15% IPC architectural uplift, but even that is dependent on other things that impacts your APU design.
You can't run it at those clocks because of the thermal impact, and even worse, to even take advantage of a CPU that fast, you need more cache... which would mean you need a bigger chip, which would mean you either gimp GPU clocks to stay within your thermal window.....etc. I could go on.
The CPU seems to be ignored because its the one area that is underutilized on any platform.