Readers always seem to think that the author has some control over the design of their books.
It is relatively easy to design for the perfect cases, when everything goes right, or when all the information required is available in proper format.
Also note that invariably when we design something that can be used by those with disabilities, we often make it better for everyone.
Isn't one of your first exercises in learning how to communicate to write a description of how to tie your shoelaces? The point being that it's basically impossible to use text to show that.