While looking for some websites declaring fully accessible, in some points they are not usable. And the other websites talking about usability are not accessible. No warning by semi-automated accessibility checker doesn’t mean perfectly accessible in real world. Pleasing visually might be usable. But it might not accessible by blind people.
What is the difference between accessible, usable, and universal design? AccessIT at Washington.edu has this:
Unfortunately, people with disabilities are not always included in usability tests. Therefore, many products that perform well in usability tests are not accessible to people with disabilities. Increasingly, accessible and universal design considerations are being addressed by usability professionals. For example, accessibility is now a topic on high-profile usability websites such as Usability.gov, Usability First, and Jakob Nielsen’s useit.com.
The National Center on Accessible Information Technology in Education.
Usable and good looking website, but lack of color contrast and semantical structures. Accessible by most difable, but lack of visual experiences.
If it works in screen readers, we can use it. But, if it doesn’t work in screen readers, doesn’t mean not usable. It is called inaccessible. Accessibility is not the only way! Go to h*ll accessibility zealots.