I think that one doesn't exclude the other. You can still write a multi-message commit with two messages: 1. Short summary of what is being changed 2. Explai

I think that one doesn't exclude the other. You can still write a multi-message commit with two messages: 1. Short summary of what is being changed 2. Explain WHY I think the point is that even if 1. is missing it can be worked-back by reading through the diff. But if 2. is missing then the future generations have no way of finding out reasons behind some decisions.