It seems to me that <jsp:getProperty> can be used without a <jsp:useBean>. In this case, the tag just do a pageContext.findAttribute() to locate the named bean. If this is true, why would we ever need a <jsp:useBean>? Why it is there?
Imagine you want to pass the attribute between request,session and application scope. There most be a way to give the attribute a unique id. then with that voila, it can be accessed outside the default page scope.
Hope it help.Curiosity is the brother of invension.