I'm new to ss games but I think the capacitor is used to keep power to the switch once activated to enable the CPU to recognize a hit. The CPUs aren't fast enough to register a fast activated switch so the capacitor acts like the switch is still on for enough time for the mpu to register it even though it has been released a short while ago. So you holding it down manually is ample time for the game to recognize it
Hope I'm correct here
