Hardware Unboxed did an interesting analysis about the doubling of the FP32 throughput in Ampere being the reason they really come alive at 4k.
Link to post with more info.
That's the correct analysis. Some graphics workload are resolution independent, as in they don't change much, relative to the pixel increase of higher resolution.
What scales with res, are compute and pixel shaders, screen space effects, RT, etc.
3080 and 3090 has far too much FP32 ALUs for its identical to 2080Ti performance in vertice, geometry, and raster. And only a tiny bit more texture performance. So its imbalanced. Requires high res to showcase the 2x FP32 gains.
Big Navi doesn't have an excess of compute like GCN, relative to front & back end performance. It's more balanced for graphics/gaming, and performs well across the different resolutions.