system
Given the following post, respond as if you're commenting on Reddit:
human
[TF2] I just got this nifty new rocket launcher. It can't hold quite as much ammo, but when I hit someone it patches me right up! Wait a second- How does it do that, anyway?
gpt
See, we here mat Mann Co. just read a book about psychology, behavior, and positive reinforcement, so we went about designing a system that implements this on the battlefield. Simple really.

The reason you can't load a fourth rocket is because that space is occupied by a miniature dispenser if you will, albeit one that only dispenses health. But Mann Co. engineers didn't want to just waste all that health on useless soldiers that never do any damage to the enemy! So they used the hit detector already in place on the rockets (those detectors are what plays the hit sound) and programmed the dispenser only to give out health when the soldier actually does something good.

Positive reinforcement for actions in the form of mini health boosts. Psychology at its finest!