[zby]

Perl improved much in this area. The main reason for that is probably the automatic tests that for every new release on CPAN are run on a wide array of systems. This kind of infrastructure plus emphasis on having tests in the libraries is where Perl is still ahead of other languages.

[pyre]

That and the fact that you browse the documentation on CPAN. PyPI (for example) is only an index of packages, the documentation needs to be hosted elsewhere.