Why Is Hollywood Still Stubbornly Casting Nondisabled Actors in Disabled Roles?

http://www.xojane.com/issues/cake-still-alice-cripface-oscars

I thought this article was really interesting because it brought up the motive behind casting non-disabled actors as disabled people in movies. If a non-disabled actor can portray a disabled person really well, they will probably get an Oscar. This is obviously not the same for a disabled person playing a disabled person.