Ignore that site , it simply means the 2600 is capable of driving a stronger gpu like a gtx 1070.
You will never get a perfect match between cpu & gpu , one or the other will always limit fps.
It makes sense to have a cpu thats more than capable simply because you can gain fps by dropping graphical settings a little in game.
If a cpu is limiting fps there is nothing you can do to counteract it, with the gpu being slightly weaker you can.
The ryzen 2600 or i5 8400 are pretty much an ideal pairing for mid range gpu's like the gtx 1060 & rx 580.
You are overthinking things.