CPAN is 20

How old is metacpan, the site that makes cpan useful?

According to their about page, it is 5 years old.

We are a relatively young open source project. In November 2015, MetaCPAN will be 5 years old. It's old enough to have become an important and well utilized part of the Perl world, but it's also young enough to have lots of room to evolve. As you will see we have many ideas and encourage more suggestions.

CPAN is an awesome tool. First, this is a good way to avoid to reinvent the wheel. Second, it's companion, CpanTesters community platform, gives to the authors a damn simple way to test their modules on a huge variety of OS and architectures. These tests are public and will help people to choose distributions according to their needs and quality exigences. Third, it encourage to test and upload modules at early stages of the development: it makes possible to simplify the development process by retrieving test results, and be sure the modules will be usable on various OS, even if they are quite old or uncommon. It's almost disappointing sometimes how for any task you need to achieve, each time there is an existing module ready to be use.

To be honest, it still is. Many of the other ones have yet to catch up with CPAN in terms of richness in eco system and breadth of offered features.

For example, i know no (and i may be ignorant) language that has a distributed library testing community.

I think it was the first better done package managers. Saved the problem of installing modules on cross platforms. Most of the time it works without a hiccup. For a perl developer CPAN is a friend.