You're trying to imply there will be a negligible difference between a 6C 4.8GHz all core clock CPU (I assume? no information provided) and a 8C 4.7GHz all core clock one.
Again, what's the reasoning behind AMD using a RTX 2080? It only benefits them to do so and it's disappointing.
You're making assumptions that the 176 FPS is the best the CPU can do and yet by your own Guru3D link proves 176 FPS is the most the 2080 can do, by the same token of you stating that with a 2080TI the 9900K would gain more FPS the 3900X could very well do the same given that its the GPU not the CPU that's the bottleneck.