DO NOT USE bottleneck calculators - they are absolute rubbish.
It really boils down to:
- Monitor resolution
- Monitor refresh rate
- Does your monitor have FreeSync, GSync, or neither?
- How much RAM do you have?
- What specific games are you playing?
And, yes, while this calculator is GENERALLY correct in that it's likely your CPU will be the weak link in the system, determining such a thing as "bottleneck" with only the CPU and GPU is a waste of time.
Modern AAA games will have the limit of 2 cores and 4 threads, but, for an extreme example, if you were trying to play at 4K resolution and 60FPS, then the so-called "bottleneck" would actually be the GPU. Depending on the game, of course.
Almost EVERY system has a bottleneck of some sort, and that bottleneck isn't even the same part necessarily from one game to the next.