A low-breathability balaclava is only a good choice in very specific situations—namely, extreme cold where you'll be doing minimal physical exertion, like sitting on a slow chairlift in sub-zero temps or taking short, easy runs. The fabric traps moisture vapor from your sweat and breath, which keeps heat in but also creates dampness inside.
The big downside is goggle fogging. Since your warm, moist breath can't escape through the fabric, it redirects straight up into your goggles, making it nearly impossible to see. And if that trapped moisture freezes against your face, you'll end up colder than if you'd worn nothing at all.
For most skiers and riders, low breathability just isn't worth the trade-off. Even on frigid days, a moderate or good breathability rating with a wind-blocking outer layer will keep you warmer in the long run by staying dry. Save the low-breathability options for those rare, brutally cold days when you're barely moving and need maximum heat retention.