I think that was a side effect of experienced Perl developers publicly explaining why Perl was not that good and why they chose another language. Others respected their authority and started repeating and so on. So, the bigger problem was: experienced developers were fed up with Perl for various reasons and started to speak up. And they were not wrong.
Many years ago there was a perl compiler, but at the time when everyone was moving towards virtualization and ease of deployment was particularly important - it got abandoned. Performance and memory consumption were never considered as problematic either, but they always were. Even simple log processing was not viable for anything, but personal homepage sized logs. It was very disappointing for many people.
As for Moose, etc., Perl had a perfectly good object system. Everyone knew how to bless a reference and make it into an object. It was hard to abuse it, nobody encouraged OOP, things were good and manageable. And yet, community decided to go farther into OOP, promote Moose, promote new syntax features, promote new ways to build modules. Things got messy in the process. Perl still didn't address any real problems, but it was a pretty much new language and a burden on everyone. Suddenly people found themselves in a position, where they needed to decide of whether they want to learn all the new things in Perl or not and learn some other language instead.
> But so do Ruby and Python, and every time I try to pick either of them up, I notice a ton of things that are as bad or worse than Perl.
I don't see them as alternatives to Perl. I think they are in decline too.