E.g. Imagine A and B want to negotiate a peace treaty. They represent large and diverse constituencies. Officially, they're not talking to each other -- there is ongoing violence, and hard-liners in both the A camp and the B camp will replace the A or B negotiators if they are deemed to be too soft.
So, there's a secret summit of A and B negotiators. Publicly, neither side can budge. However, because the talks are secret, the negotiators are free to make initial concessions to get the ball rolling.
How could making those talks public possibly be a good thing? It might actually scuttle peace and result in more violence.
It's easy for rogue elements to spoil a sensitive negotiation. There is a real need for secrecy in order to have productive negotiations on sensitive topics.
Maybe that happens once in a while. The far, far, far more common case is that secret negotiations amount to a conspiracy by the powerful against the weak.
1) Are you arguing that there should never be secret negotiations?
2) If (1), what system do you propose that would allow negotiators to break deadlocks in the pre-conditions for negotiation?
For example of (2):
A opening position: we won't recognize you unless you first give us what we want.
B opening position: we can't give you what you want until you recognize us.
Secretly, both A, B, their constituencies, et. al. would accept solution X, but they can't even start to get to X.
The point is that what people can say publicly is often much less than what they might concede privately.
This causes deadlocks, and offers griefers the ability to scuttle publicly-made plans.
UPDATE> > Without knowing what they talk about, how can you know that?
Essentially, they'll talk differently if they know everyone's listening, so that information is not as useful as you think.
Yeah, there's not a lot of them.