I very much doubt that this was a conspiracy in the literal sense of the CEOs making a secret and nefarious deal. No such explicit deal was needed. But you could explain the business decisions of the companies based on assuming such a deal, and get correct predictions about their business decisions.
I find that most of the time, it is not that useful to worry about whether there is a real conspiracy. I only care whether the conspiracy theory predicts behavior reliably.
For a political example, a lot of campaign donations come from business interests that are pro-immigration. Most voters are anti-immigration, and no politician admits to any influence by bribery. The conspiracy theory would say that the elite donors have conspired with the politicians to promote immigration.
I cannot test this theory by following the politicians into the secret meetings. But I can test it by looking at predictions. The most obvious one is that the anti-immigration candidates would be the ones independent of big donor money. Sure enuf, Donald Trump and Bernie Sanders are the most anti-immigration candidates, even tho they have very little else in common.
For another example, there are web sites that complain about White Genocide, and act as if there is a world-wide conspiracy to exterminate white Christian culture. Often Jews are blamed, altho a majority of the alleged conspirators are non-Jews.
I cannot see how any such conspiracy could exist, or how that many Jews could ever agree on anything. But that is the wrong way to look at it. What does the theory predict, and how can those predictions be tested?
The theory predicts that Europe would be flooded with Moslem migrants, and that white Christians would be blamed for all sorts of things that defy reason.
The web sites that talk about white genocide have some wacky stuff. I found one that calls Taylor Swift a Nazi! The author meant it as a compliment, I guess, but then found that others called her a Nazi for other reasons. It is hard to tell, as many of these opinions appear tongue-in-cheek.
Of course Swift is not a Nazi. But does saying that fit into a useful theory?
Consider an ant colony. The ants all appear to be cooperating in some master plan for the good of the colony. But they do not seem capable of a conspiracy, as they only have minimal intelligence and communication abilities. Even lower life forms, such as plants and bacteria, appear to act with a coordinated purpose sometimes. The conspiracy theory is a useful metaphor for explaining the behavior.
Likewise it is a useful metaphor for human groups. Lot of human groups act as if they are part of a conspiracy in their behavior, voting, and political actions.
The obvious response to this is that there is no document detailing how the group is getting its orders, and that there are individuals in the group who do not appear to be on board with the program.
But you could say the same about ants. There is no master plan, and if you watch carefully, you can find individual ants who are not doing what they are supposed to do.
People object to any group comment anyway, such as this NY Times op-ed:
The word “Muslim,” without any further qualification, and the word “person,” are, for practical purposes, synonymous.Is the NY Times really so stupid as to think that the word Muslim has no meaning?
No, it makes more sense to say that the NY Times is part of a conspiracy. They want to defend Muslims and attack Trump, but that does not explain it, because they almost surely like Trump better than Muslims. No, they hate the Americanism that Trump stands for, and so do the Muslims. The NY Times and the Muslims behave as if they are in a conspiracy to undermine America.
Stefan Molyneux made a video on How to Destroy the World. It sounds like a complete crazy conspiracy theory, until you compare it to what is actually happening in the world. Then it seems like a documentary. The only implausible part is that people are really intending to destroy the world this way. But do the intentions matter? We cannot be sure of the intentions of others, so it is better to focus on results, and on theories that explain results.