Look at how many deals with Iran and N. Korea blew up early own because one side leaked (usually intentionally to tank the negotiations) some information that meant no further negotiations would be possible.
If say there was an email from hilary saying that "The US would back X amount of billions in guaranteed loans to provide funding for infrastructure informer FARC controlled zones" one party now knows exactly how much to ask for, one party now knows a limit, one party now has more power... Or here is another example say on day 2 of the negotiations there would be some preliminary agreement on how many and what type of sentences would be commuted that's just one small point of the negotiation it hasn't been finalized but if leaked it can blow up the entire deal. FARC can say it's too little, the Colombian government/people can say it's too much, and all over something that haven't been finalized or agreed upon, on something that is likely to change 50 times over during the negotiations. You seem to think for some reason that leaking things prematurely isn't using you as pieces, it is you are a puppet of your emotions and feeding you specifically tuned information is effectively playing you like a string.
People are irrational because they are irrational.
So let's fix that first instead of continuing to manipulate the flow of information; the rest will follow.
Because our few pounds of gray matter will never be rational. Us techies tend to think we are, which is exactly why we're even more prone to act irrational in some situations!
It has become (and assuming we are still here in the future, it will become even moreso) easier to broadcast more. The primary reason people don't go around broadcasting everything is because they can't. Most people have been capable of broadcasting very little.
Consider what you are arguing (or at least, appear to be): "Yeah, we fucked you over in the past (and we may do so again in the future) and we didn't want to tell you about it (and tried not to [and will try to not tell you about it in the future]), but just play nice and give us this stuff we want, please?"
I see this argument continuing to be rejected wholesale.
Imagine trying to end WWII if every citizen of every nation in that war were sitting at the negotiating table.
A good modern example would be the middle east peace process, every time there are negotiations and a deal is on the table it blows up more often than not because of premature and selective release of information.
The selective part doesn't have to be intentionally i.e. in one side only releasing part of the information but simply because the other points were not settled upon yet.
Negotiations are like trying to balance an egg on a point of a needle, if they aren't they are often one sided.