Why carrier elevators moved to the deck edge

Why did aircraft carriers take so long to adopt deck-edge elevators?

Elevator positions depended on each navy's design priorities: protected enclosed hangars encouraged centreline lifts, while maximising aircraft capacity favoured edge arrangements.

Elevator placement followed what a navy wanted from its carrier rather than one universal timetable. British designs favoured enclosed hangars that protected aircraft, engineers, and maintenance work behind the ship's sides. American designs placed greater weight on hangar volume and maximum aircraft capacity. Moving lifts toward the edge therefore made more sense within the American arrangement than within the British protection scheme.