Remember, people locate and discover desirable content via browsing, searching and asking. Findability is just as important as usability and accessibility in the user experience.
In my opinion, website accessibility means creating an online environment in which all users, not only those with disabilities, are able to understand, interact with and easily navigate your website content.
In other words, accessibility does not only apply to people. Accessibility also applies totechnology-based users, such as search engines.
I believe that website content should be written and formatted primarily for human users. However, since people use technology to access content, I also believe that website content should accommodate search engines.
Humans first. Search engines second.
Source: Measuring Accessibility In The User Experience (UX) And The Searcher Experience