Comment by aftbit

Because if they each only have incomplete information, they each wouldn't know whether the information they have is relevant to preventing overthrow of their collective order, or intelligence that is only going to help their geopolitical adversary.

Basically, a variation of the prisoner's dilemma.

Also, those nukes we have pointed at each other are a pretty healthy hint.

Or perhaps someone with secret quantum computing can break all our encryption and has full transparency on all communications on the internet. Perhaps extraterrestrials are eavesdropping on everything I say in my living room, and sharing it with the KGB. How are we to know?

Occam's Razor definitely applies here.

"The simplest explanation is usually the best one."

Conspiracy theories are a logical reasoning black hole.

I personally feel it's generally best to avoid the mental Spaghettification.