Scenes are the engine's large-grain state containers.
A scene owns the rules for what should update, what should render, and how control should shift while that part of the experience is active. That is why the same runtime can support very different behaviors for the title screen, field exploration, battle, menus, or game over transitions.
The scene layer matters because it keeps state changes explicit. Instead of one monolithic loop containing every rule at once, each scene can focus on its own responsibilities and hand off when the player crosses a meaningful boundary.