Yeah, I think that's exactly right: I think a pyramid naturally expresses a hierarchy of categories, with the category at the top being inclusive of the lower c

Yeah, I think that's exactly right: I think a pyramid naturally expresses a hierarchy of categories, with the category at the top being inclusive of the lower categories (think Maslow's hierarchy of needs: the higher needs are only relevant once the lower needs have been satisfied). That's clearly not the case here. A misleading diagram is worse than no diagram at all.