How exactly do you know that ?
That is somewhat of a circular argument, they were not good at chess simply because they did not devote themselves to it ??
Examples of famous people won't lead us anywhere.
Just think what you do to be good at chess. You study, and you solve problems. What is the organ in the human body that does that? The brain. Therefore it follows that a better brain makes you POTENTIALLY a better chess player.
It's like asking if you need physical strength to be a powerlifter.
Firsty you have have to prove that there is a direct link between intelligence and chess,
If that were the case Einstein would have been an incredible chess player.
He was not.
What I remember reading is that Einstein thought chess was a waste of time, but in later years took it up and quickly reached a very strong level.