By your logic 7700K should do better than 8600K, because it has 8 threads and 8600K has 6.
You obsess over the thread count when it's really the overall performance of the CPU that counts.
If gaming is the #1 reason, 8600K will be ahead of 2600, for the life of the CPUs. Because even though there are more threads on 2600 those are SMT only about 30% benefit Max (much less in gaming) , the 8600K has better IPC/Cache performance, and better clock speed, which more than trump SMT bonus for gaming.
Well no for obvious reasons. Compute power wins. When all resources are in use (6 is actually pushing 6 cores). But you seem to think that I had at any point said that a 2600x would ever be a better "gaming CPU" than the 8600k. I don't think I ever said so. What I have said is that just like the 7600k now. Soon. Very soon the 8600 or 9600 will be in the same boat. They will be capped out (still in benchmarks faster) with all threads capped and when the CPU needs to do anything, even the littlest task in the back ground, the game performance will crap the bed momentarily.
You and I are talking about 2 different things. You seem locked on some god forsaken "better option" equaling best gaming CPU. I am just saying that Hyperthreading was a god send. Not for gaming, but for everything and I do mean everything else. No more thread locks no more death to a task you are running. As games utilize more cores. CPU's without hyperthreading take larger hits when something not dealing with the exact thing you are seeing on the screen happens in the back ground.
Now lets fast forward to end of 2019. Games are starting to fully utilize 6 cores.
You are playing a game at 1080p (though only res that CPU choice really makes a difference at).
You have the 8600k and a 2600x.
So in this game. Lets call it BF 1492.
You are maintaining 130 FPS on the 8600k on a completely sanitized system with the 8600k. On the 2600x you are maintaining 110 FPS.
Then you add in a couple things. Things normal people do. Like keeping Chrome or Firefox or whatever their browser open.
Both now have a consistent 120 and 100 FPS. The CPU load from the browser doesn't change much.
Now add on a content change, like current Fantasy scores or live tracker for favorite sport.
8600k since it doesn't have HT drops a full core to computer the change. Now it's only getting 90 FPS for a few moments. The 2600x with HT, can fit that work in between cycles and loses 1FPS till it is finished.
Little things like that add up. Add running Hulu on the second monitor. Have a virus scan start up. Have the system randomly need to access the swap file. Have a family member start up a video through Plex. These are everyday things that add up. That aren't just the game that everyday people do on their everyday machines that they use for gaming.
So yeah personally I would suggest looking at several things. A person who needs cores and threads. 2700x. Needs cores and threads the fastest 9900k. Wants a little breathing room but the fastest. 9700k/8700k (split between core preference, thread preference or speed). People trying to shave some dollars off of the build, I wouldn't suggest a 9600k. I would suggest a 2600x. Save more money for the video card, have a system with more flexibility, for the loss in frames even in the imaginary world where absolute highest framerate matters, but they can't spend an extra 100 on the 8700k or 9700k, even though they would be running more expensive 120hz monitors in the first place, which most don't, which most run in a GPU bottlenecked environment. There is an incredibly small niche of use cases that lead to a 8600k being the smart purchase.