on the other hand, in this specific occasion, it might be useful.
sure, Kenpachi can three (or three hundred) of them without knowing anything about their powers, but most characters aren't Kenpachi, and they could use the information.
even if they don't explain exactly how their powers work (which they shouldn't do, but should for our sake), they might reveal how their ranking system goes. which will enable Soul Society to match their forces.