I think your missing the point of the emergency channel.
The idea is to have a "known channel" or common channel for emergency radio traffic. This is not only for individuals calling out but for rescue teams, groomer operators, emergency services...etc. to monitor or scan. This way the chances of a distress being heard is greatly increased.
You also have to think outside the box and not just the "avy" scenario. Having a common channel provides an outlet to call for distress due to a multitude of emergencies. This could range from an injury to someone lost in the backcountry.
Also, not everyone in your group has to change over to the emergency channel. For example, during avalanche rescue efforts, "if" there is enough assistance on scene, then one person can be designated to change channels and broadcast the emergency, while everyone else focuses on the rescue itself.
During emergencies, stress is high and mistakes are made so by designating an emergency channel, this provides a simple, easy, known channel for people to use and remember.