Political and business negotiations are most effective when done orally.
"Don't write anything you can phone. Don't phone anything you can talk. Don't talk anything you can whisper. Don't whisper anything you can smile. Don't smile anything you can nod. Don't nod anything you can wink."
The bulk of information conveyed in a face to face interaction is non-verbal.
That's beside the point. Group decision-making happens before or after negotiations (during breaks), seldom during F2F negotiations between two delegations.