In my view, in a healthy organization, the meeting itself should be a point of collaboration. Otherwise it's a waste of time. This culture of behind-the-scenes-go-betweens also creates a lot of opportunity for opacity and malicious miscommunication (deceit).
Meetings are not the only collaboration point, probably not even the most effective. OP's advice is good advice for increasing communication and building consensus leading up to a meeting, especially if done with an eye towards transparency, as I assume they intend. Ideally you're able to get everyone aligned beforehand and can cancel the meeting. But if someone walks into a meeting blindsided by a predetermined outcome, that's a red flag that you've created an adversarial environment rather than a collaborative one. If a colleague is important enough to be in the meeting then their opinion is an important enough to affect the meeting.