For most riders, yes — a jacket without zippered vents is a significant drawback. When you're hiking to a stash, lapping the park, or even just riding hard on a mild day, you generate a ton of body heat. Without pit zips or other vents, your only option is to unzip the front of your jacket, which lets in cold air and snow. Vents give you targeted, adjustable airflow without exposing yourself to the elements.
Jackets without vents do exist, but they're typically casual or fashion-focused pieces meant for short lodge-to-lift runs or very cold, low-exertion days. If you mostly ride in bitter cold and rarely work up a sweat, you might get away with it — but even then, you'll miss the flexibility on warmer days.
If you're doing any real riding — resort laps, backcountry touring, or park sessions — pit zips should be considered a must-have feature. Skip the ventless jacket and look for something with at least underarm vents.