It comes down to the thirds rule I think. The center of attention should be placed at one of the intersections of four lines. two placed at horizontal thirds and two at vertical thirds on the image.
If the centere of attention is at one of these intersections, or near it, then the human brain finds that most comfortable and natural.
It's not so much that someone made a rule and we should follow it because it's a rule.
The rule explains what most people will find to be natural pleasing composition. We should consider it even if we break it as it is a psycological factor in the effect a phot has on people.