The real difference between the two scenarios you describe is that the incident meter is being used as if it was the first time ever, per the instructions included in the box, while the spot meter is being used as one might after years of practice and reading Adams and the rest.
What I'm saying is that both meters are equally capable of finding out how contrasty a scene is and finding the optimum exposure setting.
It is fully about using either/both intelligently. It is not a matter of one can and one can't.
For example both of the following are true:
2-The spot meter gives a single exposure value based upon intensity light falling upon the target, whether the scene has reflective tones spanning 5EV or 15EV or 8EV.