Not necessarily. Cybernetics was specifically the study of systems, so that part can also be taken as an appeal to the experts in the matter.

Generally the point of this observation is specifically about human systems, either designed or evolved. The observation stems from the fact that it's (a) impossible to ascertain what the true intention of a human that designed a system was (they may be publicly lying about it, or even privately, it even to themselves), and (b) any complex enough system has been influenced and possibly "warped" by many more than one human, so the original unique intention, whatever it was, isn't the sole guiding principle behind it.

So, if analyzing a system, rather than trying to dig into its creators' history or anything like that, it's best to just look at what the system is doing and consider that its true current purpose.