As VSarkiss says, this is not just about Perl. I'm working for an Association of Public Transport companies in Switzerland, and we have a huge database with addresses of our members, including several addresses of people who are in charge at the respective company, people who get the bills, people who get the quarterly mailing, all addresses which may or may not be the same. Now, years before I started working here someone wrote a database application in dBase (!) which sorted out all possible mailing issues for the database just fine.
in reply to The worst amputation possible: Perl proper as Open Source software
Nowadays, however, this database has become so big that that programme just doesn't work stable anymore. And because it is so huge and complex, not even the person who wrote in the first place knows how it works and what needs to be done. Still he insisted for a long time that no other database application could possibly do all that his could, and would therefore be suitable for our system.
Now, what would happen (and this applies not only for this, but more or less any such case) if this person didn't work for us anymore, or, as it has already started, didn't know enough about his own programme anymore? In the case of a serious breakdown we would not only have to immediately find a solution, but also cope with the consequences of not having access to this data for some time.
I think one of the problems here is that most people think only a custom fitted solution fits all their needs. With anything else, there would surely be something that it couldn't do or wouldn't do in the right way - which is often enough only the "right" way because it's the way it has been done for ages - never mind whether is efficient or sensible. And this unfortunately does not only (although mostly) apply to management persons.
Having said this, if we didn't have people who try to write something new just because it will do things slightly differently, we wouldn't have such a huge collection of handy stuff like CPAN. So, a little reinventing the wheel is not so bad as long as it makes sense and doesn't happen because some management type had a fancy idea...