It seems it can work for some people for some things. I think it is also possible for it not to help no matter how hard the client works. The failure of therapy to work is not always (and in my opinion not even usually) due to the client not working.
The therapist doesn't do anything really that I have seen. They sit and act like the human for the appointment time. I think it is sometimes simply time that helps or the belief in whatever part of therapy the client chooses as their Dumbo feather.
I also think it depends upon what one is looking for in terms of deciding whether it works or not.