JSF action/rendered behavior

[Dennis_Byrne]

<h:commandButton value="Cancel" immediate="true" action=""  rendered="#{myBacker.editMode}" />

myBacker is a request scoped managed bean.

When the button is clicked, the backing bean is created, but myMethod does not fire.  The runtime will not complain if @action is set to myBacker.myNonExistMethod .  

The method will fire if true is the literal value of @rendered, or if the editMode property is set to true in the constructor.

It appears as though the action will not fire, if the rendered _expression_ evaluates to false.
Can anyone explain otherwise?  More importantly, can someone educate me as to why this is a good idea?

Dennis Byrne