Speaking as someone who used Perl pretty extensively back in its heyday I’d say the difference is CPAN modules were much more likely to be self-contained, or contain a handful of external dependencies, and those dependencies were almost always self-contained.
Aah, that makes a tonne of sense. When you develop an application you're free to pull in any libraries you want, but the libraries themselves should be more careful. For them, it might be worth reimplementing some essentials.
