Why Nelson's heavy conning tower represented an older battleship doctrine

Why is reducing Nelson's conning tower described as a protection change when later ships used lighter towers?

Because Nelson's tower was armored according to older battle doctrine that the Royal Navy was already moving away from.

Later ships could reduce conning-tower weight because navies no longer valued the heavily armored command position in the same way. Nelson and Rodney retained a structure rooted in pre-First World War ideas about how admirals and captains would fight a battleship. By the time the class entered service, the Royal Navy was already considering that protection excessive or unnecessary. Cutting it from a redesign changes protection while removing weight tied to an obsolescent command doctrine.