Why four giant guns are not enough

Would a 62,000-ton battleship with four huge single-mounted guns force other navies to build equally large ships?

No. Its low rate of fire and inability to conduct effective salvo ranging would make the layout less threatening than the calibre suggests.

Gun count and mounting arrangement matter as much as shell size. Four slow single mounts cannot readily bracket a target or sustain corrective salvos with period fire control. Rival navies would have little reason to copy the calibre simply because the ship was large. A practical heavy-gun design begins around three twin turrets because it can alternate salvos and observe the fall of shot. Even that arrangement would struggle if the guns loaded very slowly.