That's the fundamental difference in opinion this disagreement is about. People simply see the relationship of the mechanics and fiction differently. Whether we use mechanics to represent the fiction, or whether we invent fiction to justify the mechanics. I don't think anyone is going to change their position on that, it simply is an different way of thinking things.
This goes hand in hand with who is empowered to invent 'the fiction' and who isn't. What's clear with the background traits is that some people are happy for players to invent fiction ('my characters knows a guy') and some aren't.