I think a good part of the issue is that right around then, Perl decided to do Perl 6. People decided to wait on doing anything big, since Perl 6 wouldn't be q

I think a good part of the issue is that right around then, Perl decided to do Perl 6. People decided to wait on doing anything big, since Perl 6 wouldn't be quite compatible. Later it turned out to be extremely incompatible. And Perl 5 would be dead long term, so why spend time on it, when you'd have to do a radical rewrite soon? Meanwhile, Python was there. And Perl 6/Raku took 15 years to finally arrive in some form, by which point Python had completely eaten its lunch.