And I still disagree with that comment that "mutable state is rampant". There are realities which we all have to take into account. To give an extreme example, should we get rid of all mutable databases and use append-only journals? That might help eliminate another class of bugs but there are a number of (practical and political) limiting factors in commercial projects.

But maybe we'll talk the same language if you give a few examples. I was under the impression that my parent poster made the point of "but your FP code gets compiled to imperative mutable code so FP is not good" or something. If I was mistaken in my interpretation then we're talking past each other.