The global economy is like a giant "Rube Goldberg" machine. It is a ridiculously complicated contraption built to perform what should normally be a simple task. Rube Goldberg machines often mimic the real world in that they are goal-oriented with many parts coming together to complete a task.
In the real world, things are usually not intentionally designed to be complicated but the reality is that they just are. It is an understatement to say the global financial system is not a well-oiled machine. More often than we would like to admit various systems and parts are thrown or "cobbled together" in a haphazard way to get the job done. We tend to try and explain events in terms of cause and effect but in doing so the bigger picture has a way of getting lost. Often hidden away is the nature of the risk that results from complexity and systems becoming codependent upon others. Bestselling author Nassim Taleb who wrote, "The Black Swan" detailed in his book how when something is highly complicated highly improbable and unpredictable events can and do occur.