I think you overstate the problem here. Chances are, unless you’ve addressed other more pertinent issues, simply using ECC memory isn’t going to stop systems from crashing in the middle of the night.
Like my desktop just froze, and then it never happened again. It only makes sense if it was a random bit-flip.
The actual RAM speed never mattered, you can't tell the difference with 150 FPS and 165 FPS (even though my screen's refresh rate is 280Hz)
10% more fps doesn't matter at 150 fps, but it's nice when your FPS is lower. 60 -> 66 might mean you don't dip below 60 as often. 55 -> 60.5 is pretty nice too. Maybe less of a deal if you've got VRR etc.
Most games still run at 90+ FPS, I would love to have ECC RAM to prevent a potential one-off crash or just to know that the RAM didn't report an error when it happened. I would pay money for this!
Better yet, the 3d cache CPUs don't care about RAM speed as much, according to benchmarks
First byte latency makes cache misses significantly slower which in turn makes 99%ile latency (which is perceived as microstutter by humans) significantly higher even if it doesn't affect throughput (fps). This was well documented way back when the first DDR5 sticks came out and they performed like crap compared to overclocked B-Die DDR4.