Why steam catapults arrived with heavier aircraft

Why did navies wait so long to adopt steam catapults despite already using steam machinery?

The system required reliable high-pressure storage, seals, and shipboard piping, and lighter early aircraft did not need that launch power.

A useful steam catapult required high-pressure steam to be concentrated, stored, and released as a controlled pulse rather than simply taken from an ordinary boiler line. Seals had to limit losses, while piping had to carry that energy through the ship to the launch machinery. Those requirements made the system a demanding piece of ship integration despite navies' long familiarity with steam power. The timing also followed operational demand: light early aircraft did not justify the complexity, while heavier naval aircraft made the extra launch energy essential.