I think there's a difference between asking applications to implement the accessibility APIs themselves and asking applications to use accessibility APIs provided by the OS.

A graphics application should be able to submit draw calls or queues to a OS subsystem that, for example, generates a comparable audio space, performs colorspace/size transformations for improving visibility, etc. Developers should just be responsible for plugging in to these systems, and the systems themselves should be as standardized as OpenGL, Vulkan, DirectX.