It is less constraining to create an adventure without attempting to make it such as the explanation for it will suit virtually all campaigns. That is a no-no these days, and an author is castigated for not treating GMs as unimaginative and non-creative clods whose hand must be held at all times. Rather akin to how some think players' characters must be coddled in regards to perils in adventuring. --Gary Gygax on EnWorld, March 2007.
If anything describes the old-school approach to commercial adventure (and setting) design, that does.