To the contrary, it seems to me that most people who use Perl at some point never deal with, let alone learn to handle, "adult code". Interview people who list Perl on their resume (and actually used it) and see how many have not, for instance, learned how references and objects work.

Even though this is not a particularly esoteric feature either of Perl or programming, I am confident that you will find that most have not. And God forbid that you should ask about a feature like closures which has not been hyped in various big name languages for the last decade. Most people at least feel obligated to say that they have heard of OO and planned to learn it at some point...