That may be true. Though you could probably make the case that the optimal physical requirements for a center are rare as well, especially at the NFL level. If those requirements don't correlate with intelligence then centers are being selected partially for intelligence.
From my experience playing football offensive linemen and quarterbacks have significantly higher mental requirements. Personally, I always found keeping a complex offense straight against any potential defense more stressful than actually dealing with the defenders. My role on any given play wasn't set until the ball was snapped (or later). Most skill positions knew what they were supposed to do as soon as the play was called.
From my experience playing football offensive linemen and quarterbacks have significantly higher mental requirements. Personally, I always found keeping a complex offense straight against any potential defense more stressful than actually dealing with the defenders. My role on any given play wasn't set until the ball was snapped (or later). Most skill positions knew what they were supposed to do as soon as the play was called.