How did economists know that the econometric models "didn't work?"
And then the whole effort was basically abandoned, because the models failed to outperform mindless trend extrapolation -- or as Kevin Hassett once put it, "a ruler and a pencil."
The model predictions were able to be compared side-by-side to other predictions, and to observed reality. When that is attempted with climate models, and the model predictions are found lacking, we're told that the timescale isn't long enough. "We must wait longer to see the true predicted effect." But you can bet your Aunt Petunia that the timescale would be "long enough" if there were any agreement whatsoever between the models and the actual climate.