[Rain Man]

Maybe they take less because they get to touch the ball on every play and that's prestigious to other linemen.

Or maybe guards do more pulling or second-level blocking that requires more mobility.

Or maybe there's a smaller market for centers since teams need twice as many guards.

Or maybe it's a throwback to colonial America when centers were confused with sinners by semi-literate populations and shunned accordingly.

Or maybe it's easier to exist with symmetry around you, so centers are the most balanced, followed by guards, followed by tackles who have to deal with congestion on one side and open space on the other, which is challenging for their mental health.