Indeed, generational improvements are at an all time low. Most of the "revolutionary" AI and/or GPU improvements are less precision (fp32 -> fp16 -> fp8 -> fp4) or adding ever more fake pixels, fake frames, and now in the most recent iteration multiple fake frames per computed frame.

I believe Nvidia has some published numbers for the 5000 series that showed DLSS off performance, which allowed a fair comparison to the previous generation, on the order of 25%, then removed it.

Thankfully the 3rd party benchmarks that use the same settings on old and new hardware should be out soon.