Accessibility is about making the UI usable for everyone - that happens to include handicapped people (who often do require specific accommodations, such as reduced animations, TTS, zoom, color filters...), but that also includes power users (who e.g. need to do some specific task often enough, that they might benefit from the UI being scriptable), people who sometimes need to use a computer late at night (automatic dark mode), people who need to stay focused on a specific set of tasks (do not disturb with per-app notification filtering that syncs across devices), etc etc etc.

It's this "oh it's for the handicapped" mindset that makes UIs unusable for everyone.