For questions about what mechanical system is the best match for games in a particular setting. The system must promote gameplay that creates or encourages the desired setting features.
A gritty, deadly fantasy setting should be paired with a system that makes death a real (and perhaps permanent) danger.
A high school drama should be paired with a system that features social conflicts and tracks social currency. Emotional states should feature as prominently as physical states.
A system-for-setting question should specify the setting features that should be mechanically supported. An answer should explain how those features are supported by the system.