DigitalFoundry had an interesting take on frame rate/frame time performance on Intel/AMD. If you look at the graph you can see Ryzen dip down more for a few times when there's more computation or memory throughput needed.
unless you are compiling chrome in the background or streaming, you're not going to saturate even eight cores while gaming. in most benchmarks I've seen, the 9900k still performs better while streaming.
okay, what parts are we talking about then? aside from the 3900x, the Intel parts all have the same core count as their amd counterpart at similar price points.