The decision
Meaningful copy, navigation, and controls are rendered as semantic HTML before cinematic layers are added. WebGL is treated as atmosphere, not as the only route to content.
Reduced motion removes continuous and scroll-linked effects without removing the sequence, relationships, or invitation that those effects support.
What this protects
This boundary protects battery life, low-powered devices, assistive technology, slow connections, and visitors who prefer a quieter experience. It also protects maintainability by keeping narrative structure independent from a rendering engine.