An excellent breathability rating isn't overkill if you ski hard, run hot, or constantly battle goggle fog. Balaclavas with this rating use highly breathable fabrics or mesh zones that let sweat vapor escape fast, so moisture doesn't build up and fog your goggles—even during high-exertion skiing like touring, moguls, or tree runs.
The tradeoff is that maximum breathability often means slightly less wind protection and warmth. If you typically ski in bitter cold or run chilly, you might find these models feel a bit drafty on the chairlift or at speed.
That said, if fogging is your number-one frustration on the mountain, excellent breathability is worth prioritizing. You can always add a neck gaiter or rely on your helmet for extra warmth, but you can't easily fix a balaclava that traps moisture once you're out there.