You're acknowledging this the wrong way.
If the i7-6700K was bottlenecking, then everyone would be experiencing a bottleneck.
The i7-6700K is the top gaming CPU at the moment (Not counting 6800K+) that is for the 'General gamer etc' if you know what I mean.
No AMD Processor at the current moment (Zen might change this) can beat the 6700K.
Intel has much more efficient and strong cores compared to AMD, who have more, weaker and less efficient cores. Hence why Intel is much more expensive and the current top processor manufacturer.
Because it uses cores more efficiently, it is getting optimised for CPUs that have those cores, still doesn't mean 'more cores the better' as in most cases, 8 cores aren't even used.