The opt-out most designers never see
Every major operating system has carried a reduced-motion preference for years. Apple added it to iOS in 2013, initially to address complaints about the parallax home-screen effect triggering nausea and disorientation. Android followed. Windows has offered "show animations" as a toggle since well before that. The preference is real, has a real API — the prefers-reduced-motion media query, standardised in CSS Media Queries Level 5 — and connects directly to that system switch. When a user enables it, they are making a deliberate, often medical, statement about what their nervous system can tolerate.
The population who use it is not negligible. Vestibular disorders — conditions that make motion on a screen cause genuine physical symptoms, from dizziness to nausea to disorientation — affect a significant minority. The Vestibular Disorders Association estimates that roughly thirty-five percent of adults over forty have experienced some form of vestibular dysfunction. That figure encompasses degrees of severity, but it maps to a real slice of the people using an interface on any given day. Add users with epilepsy-adjacent photosensitivity and those with attention disorders for whom scroll became a projector of relentless kinetic noise, and the number of people with a legitimate stake in the reduced-motion preference becomes harder to wave away.
The usual counter-argument is that animation communicates: it shows spatial relationships, confirms state changes, directs attention. This is true. Nobody is arguing for static screens. The prefers-reduced-motion query is not a demand to strip all motion; it is a signal to substitute. A fade instead of a slide. A crossfade instead of a parallax push. The element appears; the user understands it has appeared; nobody's vestibular system has been assaulted by a 400-millisecond spring physics curve nobody asked to experience.
What the query reveals, when you look honestly at which studios are honouring it, is which motion was communicating and which was decorating. The entrances that dissolve quietly still convey hierarchy. The ones that stop working when the scroll-jacked parallax is removed were never load-bearing. They were atmosphere — or, less generously, they were the product of a brief that said "make it feel premium" without specifying who gets to feel comfortable enough to stay.
Checking the query takes three lines. Providing a reduced-motion path takes a decision about which animations matter. That decision is harder and more clarifying than it sounds, which may be exactly why it is so rarely made.