Since we're 10 years on at this point, I feel pretty confident saying the plateau to my eyes landed somewhere between the PS4 in 2013 and Pascal (GeForce 10-series) in 2016.

I've kept playing games and upgrading my GPU every other generation, and they're still fully utilized, but I can't really see where the additional compute and money is going. My biggest visual upgrade during that time was actually going from LED to HDR OLED which is something that requires virtually no additional processing power.