You have a perl app named someapp.pl. With the app is a spec on how to create plugins for the app. The plugins go into /etc/someapp/. Sharpdevelop does this very thing (but it's not Perl). There's a spec on how to create a plugin and it will load all plugins in the plugin path.

I'm not saying that the person who asked the question was even intending this, but how is it your or my place to tell someone their wrong without even knowing what they're doing? If something seems suspicious, tell them you're curious as to why. But again, just because you can't see a valid reason doesn't mean that there isn't a valid reason.