To me Perl was just Weird, to no particular end. Not the kind of mind expanding Haskell/Prolog/Lisp weirdness that opens up new possibilities. It just does roughly the same things as every other language, but everything is done slightly differently due to evolving out of the primordial soup of bourne shell and AWK filtered through Larry Wall's brain.

Perl and Python were similarly powerful and useful languages, but I could learn and start producing useful code in Python after reading an hour long tutorial. Perl took an order of magnitude longer, and remained more awkward to use just due to the Weirdness. There was a momentum building in the early 2000s toward competitors like Python and Ruby that were seen as less crufty and more modern.

Perl's developers seemed to agree, since they cooked up their own competitor to Perl, an entirely different language confusingly called Perl 6. The coexistence of Perl 5 and 6 made the Python 3 transition look like a cakewalk -- at least it would have save for Perl 6's almost entire failure to exist for over a decade after its inception. It produced lots of constantly churning specs and blog posts about register based virtual machines with native support for continuations or whatever, but no implementation of a language that anyone felt comfortable using for any real development. Meanwhile people kept using the ossifying Perl 5 for existing applications, and gradually transitioning away as they were replaced.

Also PHP overtook it for the "just FTP a script to $5 shared hosting and make a webapp" use case.

I agree, and the blame for its weirdness can be laid directly at Larry Wall's feet, because Wall wanted a language that allowed for cleverness, suprise, and ingenuity. He was never happier than when someone would come up with a completely new way to do something. For Wall, programming was less about coding an outcome, than it was about speaking a particular language (and ideally, writing poetry in it). And it was very successful in this way, and fit reasonably well with the high-knowledge users/environment of unix in the 90s.

It's just that Wall's vision was incompatible with general purpose languages used widely by a wide range of knowledge and skill amongst its users, and as unix/linux opened up to that wider range, better general purpose alternatives were chosen. Having to learn to be a poet to be a good coder was too high a barrier.