That analogy would only be valid if people drove their corvettes in real life with S rated tires for the most part. AtenRa's testing represents how I think most gamers actually use their PC. It isn't isolating just the CPU if it's GPU limited, I get that, you are right. But I think most people actually game at mostly GPU limited settings.
This has been heavily discussed but I'm of the opinion that CPU bottlenecks are much worse than GPU bottlenecks in real life scenarios. I accept that many gamers are GPU limited, and that's a good thing.
A GPU bottleneck causing unusable FPS can be fixed easily by changing resolution/detail settings.
Also, people upgrade GPUs more often than CPUs. If a rig has sufficient CPU to be GPU limited that means it will be a good candidate for a GPU upgrade. When the new 14/16nm GPUs come out soon it will trigger an upgrade cycle and I predict we will see a lot of people will find themselves with GPU heavy/cpu light rigs.
In other words the maximum potential of CPUs does matter, even for people who don't buy top end GPUs.