@st3v30 fair enough. You highlight an area where more CPU power can become especially important: achieving very high (~100+) fps. But if you're aiming for 60 fps gaming, which I feel is the majority of people, I doubt there's many cases where a 6700k could hack it but a 6600k couldn't.
Those benchmarks are somewhat unrealistic, as basically no one is going to be using a Titan X/GTX 1080 for 1080p gaming. And in that Techspot article for GoW 4 you'll see that as soon as they drop down to a 'weaker' card (Fury X, 980 Ti, GTX 1070), framerates for 6700k and 6600k become quite close.