Imagine your git history filled with commits from project managers where every little change in requirements and docs has its own commit. We've tried that and ended up having to rebase our branches multiple times a day while we lost the overview of code changes completely.
The main issue that code can live in multiple branches while development but you can't apply that to docs and requirements where you need to have one centralized source of truth for everyone.
I think we will start to see more adaptation from collaboration tools to provide/accept the info in text format making it suitable for agents as a working solution. Meanwhile, I've seen that having two repos (One for Code and one for docs) is the best solution for the current tools available