Gosh, that would be great, wouldn't it!
Sadly, not all games are created equal, not at all game engines respond as well to one set of hardware or another, and as such most developers create games with the lowest common denominator. So most of the time, you get a minimum set of requirements to run a game at it's basic settings (whilst theoretically it being an enjoyable experience - which is debatable) and also having recommended settings to allow for best visual experience, and thus a more enjoyable game.
The best solution, is to be aware of such limitations, and having slightly more grunt than is normally required.
With that said, there are very few games which demand more than 6 true cores, for a top experience in game. Some do. Games like BF V for example use my 6c/12t CPU at about 80%. But depending on settings, you could still have a good experience with a 4c/8t CPU. YOu just have to dial back settings and expectations to adjust for a slightly weaker CPU.
There is no hard and fast rule. But certainly it's important to have a good idea of gaming performance.
Something like this is useful :
https://www.game-debate.com/search/games but only as a guide. One person may not care for visual effects and only want max FPS, Another might want all the beauty that game engines offer, with the expense of FPS. It's different horse for different course.
But I would taper that with the fact that, not only are all games created equally, but most system configs are not too. A developer can't factor in every single variation on a build, so it comes down to basic stuff, like how much ram, a capable CPU/GPU etc. There are simply too any variations, to have an accurate piece of software that will say, this CPU, that GPU, this amount of ram will make the game run great. But the recommended specs are a guide. That's about all you can expect I'm afraid.