It seems that most games are not cpu limited if you're anywhere under 80 fps. You really have to crack into super high frame rates to bottleneck on the cpu.
It's probably a truth, but I'm playing almost exclusively WoW and it's known that even 7700K wasn't able to sustain 60 FPS in hard conditions, limited by CPU single-thread. So for some games single-thread performance is all that matters, unfortunately and it pushed into Intel direction if you want the best configuration.
Being limited by CPU/GPU depends a lot on what kind of hardware you have for each. For example, I have a 1070 and an i5-4690k and I'm CPU limited in some games (below 80-100fps)
Depends on the game, too. Guild wars 2 annihilates my i5-4670.