Is the purpose of a system really what it does though? Obviously there are side effects and tradeoffs in any complex system. Is the purpose of a vaccine to make you sick - no, but that is a side effect of some vaccines on some people.
If we apply the "purpose of a system is what it does" to itself, this methodology is more a way to generate interesting (and cynical) hypotheses than to get at the truth.
If we apply the "purpose of a system is what it does" to itself, this methodology is more a way to generate interesting (and cynical) hypotheses than to get at the truth.