GPU power hasn't been increasing anywhere nearly as fast as CPU power -- the mid-range CPU that i have in my PC right now is like 5.5x weaker than a mid-range CPU you can buy today, but a mid-range GPU from the same time period is about 2.7x weaker than a mid-range GPU today (i5-4440 vs AMD Ryzen 7 3700X, GTX 670 vs RTX 2060, mostly in same price range +-$50, stats from passmark)
you can totally get away with buying a much weaker GPU from a few years ago instead of shooting for the best model rn, since it sort of seems like GPU power hasn't been increasing all that much. plus, most games allow you to tone down the GPU load to an absolute minimum, you don't really get that option with CPUs most of the time
honestly i think that's really interesting. i would love to do some research and figure out the technical reasons for the discrepancy. also, really hoping that the RTX 3000 series breaks the trend and increases its power by a lot, would be really cool :)