I have i7 6850K and 5930K systems as well as i7 920, 930, 960, 980X, and just upgraded my i7 7800X to an i9 10920X. In terms of tangible gameplay experience we have not seen the chains move too much ssince 2012/13.
I upgraded from a i7 960 to an 8700k and I did it for the NVME slots and other motherboard improvements mainly. I suspect the next time I upgrade my MB and CPU again will be for similar reasons: ie to get more nvme slots, pcie 4 and 5, etc etc. I seriously doubt I'll upgrade the MB/CPU because of a lack of CPU performance.
Honestly this is exactly why I tend to argue with people who say that motherboard compatibility over CPU generations is a good reason to pick one vendor over another. The difference between the first generation ryzen and the last gen ryzen on the previous motherboard pinout wasn't large enough to warrant an upgrade for most gamers IMO. They would be far better off with a better video card 99% of the time.
But between zen 1 and the current zen 4 you go from pci3 to pci5 and ddr5.
So even if I *could* upgrade my 8700k to a faster CPU in the same socket I wouldn't because id be more interested in the extra MB features than I would in the CPU performance improvements between my 8700k and the current gen intel CPU.
Now when I was a teenager and upgrading from a 25mhz CPU to a 66mhz or 100mhz CPU than it absolutely was a giant leap up when you swapped that CPU out!