The people that are likely to code something equal to or better than what's on CPAN are also the same people that aren't likely to be asking about it in a public forum (except perhaps the small public forum of an IRC channel where they know several perl gurus are lurking).

For the majority of cases, people are trying to solve a problem. To get work done. To meet a deadline. To get this problem out of the way so that they can get on with the stuff that they are really interested in!

As a first approximation, "use a module from CPAN" is the best answer to give. If someone really wants to learn how to do it themselves so as to better understand perl or the "it" that is their problem, there's nothing stopping them. If they lack the fortitude to press on in the face of an existing implementation, then I say that's Darwinism doing it's thing! :-)