The thing is, they're only "crazy theories" until it's leaked or found out that they're valid. Don't get me wrong, some are straight up looney, but others are quite practical. The best way to discredit that which threatens you is to say its "crazy".
But at the same time, most conspiracy theories are so vague that it is impossible to disprove them. Without a way to disprove them how do you sort out the legitimate concerns from the theories that are a lot bit looney? There has to be some reasonable excuse to ignore them, and if you can't disprove them the only way to do that is to call them crazy. Just like every Buzzfeed list relates to your life, some conspiracy theories are bound to be right about something, even if they got all the details wrong. And something about a stuck clock...
The content matter of conspiracy theory de jour is not the issue and entirely irrelevant. These theories are proposed in response to the obvious and glaring wtf-ness of the official stories pushed by establishment organs. The degree of information gap is directly correlated to the far-out-ness of the proposed theories. What you need to note is this: The Guardian is pushing the establishment line that "secret plots" do not, in any shape or form, inform the unfolding of 'history'. It is a "crazy" notion, but you have been informed of the 'red line' of polite conversation.
Maybe the value that such " theories" bring to society is to prompt the citizenry to question that which is sold to us as objective fact. Questioning power is not just our right, it's our duty. As such, I appreciate the role that "conspiracy theorists" play.