By the time Perl 6 was around, Perl's lunch was already eaten by Python. Only a few table scraps left. Perl 6 would have had to be a better Perl 5 and a better Python 2 to win.
Python came with better batteries and better syntax. It allowed producing code you could read and understand a week later. Perl I found was a write-only language for me. I went back looking at my old Perl code and I couldn't decipher it without some effort.
And Python became popular not just because it was a better Perl, but it attracted folks who used Java and C++. CPU speeds were getting fast enough that you could actually do file and network IO at acceptable speeds without all the `public static void main(String[] args)` and `System.out.println(...)` boilerplate, but still had all the object oriented bits like inheritance and composition with which you could go crazy with if you wanted.
I think the article's author is implicitly not considering that people who were around when Perl was popular, who were perfectly capable of "understanding" it, actively decided against it.
It's a little bit of a tragic irony that the better a job you do, the less likely it is to be noticed. (: