If you are unaware, batoning is a valuable survival technique. If you are in a severely damp environment such as a rain storm or snow storm, any smaller size would can be soaked to where you can't start a fire with it. Severe dampness mixed with low temps increases the chances for hypothermia. In such conditions, the ability to start a fire quickly is paramount.

Batoning allows you to split large diameter wood to get to the dry heartwood quickly to allow you to start a fire with dry wood. You may think an axe would work better, but it is impracticable to carry for long hikes, and is more dangerous to use with an increased chance of injury compared to batoning.