This is not entirely accurate. I found out with the second generation Threadrippers that while their benchmark numbers showed they were good enough for 4K gaming, they actually weren't. The had lower lows and higher highs than other CPU's leading to a similar average but actual frametime analysis proved that they were incapable of providing a quality 4K gaming experience. At the time, only the 9900K was capable of maintaining a solid 60FPS+ framerate and none of the AMD CPU's I tested (which included the Ryzen 3000 series and Threadripper 2000 series) could do that.
Granted, these aren't the CPU's being sold today and trying to build a 4K rig out of parts that old would be a waste of time and money today, but I think the point still stands. These types of issues are why I think testing at 4K in CPU articles makes sense because internal latencies with CPU's or other failings could be an issue for gamers or professionals that might also use their workstations for gaming.
But I agree with you in that for the purpose of a 20 game roundup, 1920x1080 is what makes sense. I would tend to think that the best CPU's at 1080P are going to be the best CPU's at 1440 and 4K resolutions as well. (Data over time has usually confirmed this as well.)