Still, there's diminishing returns on more cores for such uses. You can use 2 cores, might use 4 cores, having 6-8 cores is probably just cause excess heat that could be instead spent to run 4 cores at higher frequency.
Strategy games can also be GPU intensive if they implement neural nets instead of heuristical models
1) Games are becoming less CPU-bound and are putting more work on the GPU, so the CPU matters less for gaming today than it used to.*
2) Vulkan and DirectX 12 make multi-threading easier and more efficient, so there is more incentive to adopt a parallel architecture with those APIs.
* Of course, I'm generalizing. Strategy games, for instance, are still very CPU-heavy and likely always will be.