Well, that simple explanation makes sense, of course. But if you think about it; the difference between the success and failure of the 'perfect crime' ususally hinges on a 'devil of a detail'.
Man/made disasters (fires in California for example) have been the result not a great plan gone awry or for that matter a 'mission accomplished'; but rather the devastation hinged on the most stupid/selfish/inane of choices. That is life.
We almost lost a couple of states to fire a few years ago. The existence and magnitude of this fire seemed to deserve a reason at least equally grand - an 'act of God' or an act of evil would have been more acceptable than the reality.
As it was, we had to accept the petty truth - a woman Forest Ranger decided she would feel better if she burned her boyfriends love letters in the mountains they used to enjoy together.
But the fact that the 'great' can often be generated by the extremely simple; does not make it a 'law of the universe'.
Conspiracies DO happen. The conspiracy can be as reasonably planned to create a horrific event, as they can be reasonably assumed afterward.
It is also true, that people are more comfortable with the known vs the unknown. Putting a name on it - being able to 'wrap your mind around it'; allows many unacceptable or confounding elements of life to be dealt with efficiently.
For some that comfort is the 'Warren Report'; for others, there is more comfort in the reasonable challenge of the 'conspiracy'.