Clear headings help screen-reader users navigate, and they help someone skimming on a phone. Captions serve deaf viewers, and anyone watching on a crowded train.
Good defaults help every reader
Accessible design is mostly a set of good habits: meaningful alternative text, visible focus states, sufficient contrast and forms that explain their errors.
Accessibility is not a feature. It is quality.
The teams that do this well treat it as part of the definition of done rather than an audit at the end.
