Interestingly, i promise you they do not use a so narrow definition. Dr Richard Cook is one of the leading researcher in this particular space. His definition of "complex system" is used here indeed in that wikipedia definition you provide and the way they fails may seem spectacularly different, but the research in them have shown that they are not so different and all stems from the same "laws of nature".
I would be happy to provide links to the research if you are interested :)