The purpose of most studies like this is not simply to establish a binary yes or no, but to measure, quantify and explain how something works in more detail than is currently known.
People knew that you would die if you were kept from breathing, but they didn't really know why that was, nor did they know the exact action by which breathing even occurred postulating that it air entered the body through the skin, or perhaps air somehow was necessary to cool the heart which at the time was theorized to be where all thought occurred.
