You two are both right. You both cite credible sources that echo your sentiments. It'd probably be better just to decide that there is no universal code of music classification. There are just a whole bunch of experts, with varying degrees of self proclaimed authority, with varying numbers of followers. Remember that there are no forests without trees. Music classifications are forests and songs are trees. If you spend all your time trying to study forests, you won't be spending any time studying trees. Trees are what we actually enjoy. Forests just make conversation quicker and less wordy.