I won't attempt to speak for Dweck but having read her book I don't think she was at all advocating turning "good job working hard" into the contemporary substitute for "good job" (which was really the replacement for the "good boy" a generation ago). She's not advocating a constant stream of praise and thinking that's cool as long as it is hard work.

And, I'm agreeing with the point made by gratified. There is no substitute for students having access to work that is actually challenging enough that they get to make mistakes, experience frustration, and actually get to work hard. Nothing adults can say is a substitute for those experiences.