AmbientLight.fx disappeared from the installation repositories, why?

It was in Legacy Standard Effects package until version 5.0 but now that package is gone.
The list has been expanded to include several hundred shaders now but this one is gone and I'd like to know why that is, if anyone has any insight.
 

Legacy shaders included shaders where the author have disappeared or otherwise stopped updating and nobody took over either. Don't know why those would be removed altogether.