> what POSWID actually means

The phrase does not make more sense even if we go all the way back to Beers. I certainly don't feel alone in not understanding how he went from his (fair) observation that "[There's] no point in claiming that the purpose of a system is to do what it constantly fails to do" to his more controversial conclusion: "The purpose of a system is what it does (aka POSIWID)".

Surely, there were many more sensible (but perhaps less quippy) stops between the two.