Perl's decline was cultural

In fairness, Perl died because it was just not a good language compared to others that popped up after its peak. Sometimes people just move to the better option.

Perl is a great language, the way Scala and Haskell are great: as openly experimental languages, they tried interesting, unorthodox approaches, with varied success. "More than one way to do it" is Perl's motto, because of its audacious experimentation ethos, I'd say.

Perl is not that good a language though for practical purposes. The same way, a breadboard contraption is not what you want to ship as your hardware product, but without it, and the mistakes made and addressed while tinkering with it, the sleek consumer-grade PCB won't be possible to design.