User input elements must have appropriate roles, whether native HTML or a custom widget, to convey to screen reader users their meaning when landed on and given focus. If a custom widget, appropriate ARIA role values must be used instead of abstract roles to correctly expose the purpose of the element.
Elements in the focus order need a role appropriate for interactive content so that screen reader technology can communicate that information to users.
If interactive content elements do not have appropriate roles, the role will not be able to perform the accessibility function intended by the developer.
When screen readers and other assistive technologies do not know the appropriate role of each element on the web page, they are not able to interact with it intelligently, nor are they able to communicate the role to the user. When the value for a role is not valid, there is no way the HTML element's set of features, properties, and methods of conveying information to and/or from the user can be communicated via assistive technologies.