That's some dinosaur games from the past. Modern games are using all available CPU cores with something like Vulkan and saturate GPU fully. So Intel CPUs are left in the dust with all the cores you get from high end Ryzens.
There should be a formalized law for this - anything that was once widely known as true (because it was) will continue to be treated as gospel far after it ceases to be the case.
And when challenged by the new norm, the old guard repeat their gospel louder and in greater numbers! So if you hear some technological rule of thumb repeated often enough, you should doubt it even more than if you hadn't heard it at all.