Because that's not the theory that the data supports? As I understand the current article, the data does not support a single explanation. It's a combination of

Because that's not the theory that the data supports? As I understand the current article, the data does not support a single explanation. It's a combination of many things, working in concert. The issue is not coming up with an explanation that makes sense. The issue is coming up with an explanation that actually explains as much of the data as possible.