As I said robots. Here, let me play part-time psychologist.
You both think genres are stupid. You've ranted about it, you'd cited examples that show that its ridiculous, you've tried to have high minded discussions, you've even tried to get down to the nuts and bolts and create some sort of musical Pangaea argument.
Now, to prove a point you're clinging to with a death grip and horseblinders on, you're going to suck to logical definitions.
You're free to do what you want, but heres why thats stupid. Language, especially english, is not for grammarians alone. In fact that are afterthought to those who actually create language, so just because definitions are assigned to things, in a living language they have other connotations.
For the same reasons reasonably intelligent people don't keep making the same terrible joke of "Whats so civil about war anyways?", we don't constantly go "Isn't almost everyone a singer/songwriter?" Do you plan on getting into battles over how much of the writing must be done by you to get credit? If I change two worRAB, am I a writer?
Singer/Songwriter has become synonymous with troubadour, with introspective music, with responsibility shouldered by 1 or 2 people.
I'm aware someone in many banRAB sings and writes, and even though those worRAB are in Singer/Songwriter - its not what it means. If you don't like that people use the word, invent a new word.