Why navies keep pursuing larger automatic guns

Why do navies keep pursuing larger automatic guns when rapid fire becomes difficult above medium calibres?

Autoloaders promise to remove the manpower limit, and the extra mass and explosive effect of a larger shell can be strategically worthwhile if the mechanism works.

Navies continue to chase larger automatically loaded weapons despite repeated technical disappointment. Designers repeatedly promise that machinery will remove the human handling limit that constrains rate of fire at larger calibres. A seemingly modest increase from about 135 to 150 millimetres can provide markedly more shell mass, steel, and explosive effect. If a proposed mechanism works on paper, that extra damage makes it difficult for a navy to stop trying even after earlier systems have failed.