Why deck-edge lifts were not adopted immediately

Why did navies take so long to adopt deck-edge aircraft lifts?

Earlier centerline lifts were cheaper, strong, and compatible with armored hangars, while deck-edge lifts became more useful as aircraft size increased.

Centerline lifts were cheaper and structurally simpler at earlier technology levels. They were also quicker to build and inherently stable, which mattered on smaller carriers. In the British case they fitted an armoured hangar whose protected sides were part of the ship's defensive scheme. Deck-edge openings therefore traded some established structural and protective advantages for greater operating flexibility. Their later adoption reflects changing aircraft and ship requirements rather than an obvious solution that earlier designers simply overlooked.