When a system is set up to accomplish some goal, a new entity has come into being -- the system itself. No matter what the "goal" of the system, it immediately begins to exhibit system behavior; that is, to act according to the general laws that govern the operation of all systems. Now the system itself has to be dealt with. Whereas before, there was only the problem -- such as warfare between nations, or garbage collection -- there is now an additional universe of problems associated with the functioning or merely the presence of the new system.
Large systems usually operate in failure mode.
The larger and more complex the system, the less the resemblance between the true function and the name it bears.
What the system is supposed to be doing when everything is working well is really beside the point because that happy state is never achieved in real life. The truly pertinent question is: How does it work when its components aren't working well? How does it fail? How well does it function in failure mode?
Any change in status quo prompts an opposing reaction in the responding system.
(All of this via Paper Bits)