The case, without exaggeration.
THE PEOPLE
A meaningful proportion of any audience has some impairment affecting how they use a website.
Most of them will not tell you. They will leave.
THE OVERLAP WITH GOOD PRACTICE
Most accessibility measures improve the site for everyone: readable text, clear structure, descriptive links, keyboard usability.
THE SEARCH BENEFIT
Alt text, heading structure and descriptive links all help search engines understand content.
Real, and secondary.
THE LEGAL POSITION
Requirements vary by jurisdiction and sector. Public bodies and larger organisations frequently have explicit obligations.
For a small private business the position varies, and the practical case is strong regardless.
WHAT IT COSTS
Most measures cost nothing if built in from the start: contrast, alt text, heading order, form labels.
Retrofitting is more work, which is why starting right matters.
WHAT NOT TO CLAIM
Full compliance with a standard you have not tested against.
A false claim is worse than none.
THE PRACTICAL POSITION
Do the straightforward things. They cover most of the benefit.