Perl's decline was cultural

Nobody will agree with this hot take, but I was around in the perl years, so maybe take this opinion with a grain of salt:

Perl wasn't arcane on purpose, the bar for being a programmer was just that much higher, born through necessity as we didn't have as much material to easily turn someone into a capable engineer, so to make anything work you had to -really- be motivated to learn, and that extended to the entire skill tree of things that happen before learning to code, like simply navigating the machine and being able to reach the realization that you needed to write something on your own.

Perl evolved to suit the needs of those that used it at the time, and it reflected their interests, skills, and abilities.

These days everything is so abstracted, so available, so easy, all of the material to learn literally anything is free and at your fingertips, programmers don't need to be that knowledgeable to identify a need and generate some code that mostly addresses that need.

There were programming envs that were easy to pick up in contemporary times. Hypercard is one that's often especially-fondly referenced as a non-traditional-programmer friendly example. Basic was much less arcane syntax-wise too. It's been a LONG time since I used Pascal but I also remember it being simpler to pick up.

But Perl specifically came out of a fairly arcane sysadmin-y corner of the world full of other already-arcane tools like awk and sed. And those were a decade older, but by the late 80s they weren't the only thing around to compare to.