In my opinion, those are results of Perl losing mindshare. Numpy is not exactly hard (R has a significant fraction built in, and there's an old standard library for Scheme, of all things, that is very similar). Perl was perhaps the leading language for websites, but the Perl 5/6 situation just confused everybody as it dragged on, which made Python and Ruby libraries seem more attractive.
> And I guess Perl also never had its Django (or Rails).
It’s got two of them - Catalyst (older still works fine) and Mojo - newer and shinier.
I think python is a better fit for mathematical work. I like to say that python helps you think more like the computer does, and that perl helps the computer think more like you.
rails as far as I understand is opinionated and optimised for CRUD / database type applications. Catalyst is much more agnostic about the model you use. It provides the flexibility and a way of structuring the code and providing debug tooling that makes structuring a decent size app well reasonably easy to do.
So it's the Osborne effect? Where you stop using Perl 5 because you're waiting for Perl 6 (announced in 2000, released never? As Raku? As a rolling release? The history appears confusing in Wikipedia.)
Perl 6 was released as language spec and on the Rakudo implementation; the rename to Raku was kind of a backformation from the name of the Rakudo implementation, but it was after the first stable release.
Perl 6 had its first official release in December 2015. It has since been improved, mainly in performance and in async / event driven capabilities. It got renamed to Raku last year (https://raku.org using the #rakulang tag on social media). You can check out the Rakudo Weekly News if you want to stay up-to-date: https://rakudoweekly.blog
