The syntax, full of @ and %, was convoluted and made you have to think about more things compared to Ruby or Python without giving you that much apparent power or benefit (as opposed to when you'd need to think about types more in Java or a C-family language).
Neither Ruby, Python, nor Perl were in my first three languages (Pascal, C/C++, Java were those). Ruby, Python, Matlab, R, and Perl all came later for me, within a few years of each other. Perl did not have anything like the approachability of Ruby and Python coming from that Pascal/C/Java background.
(IMO Python is losing some of that now, especially like in the last project I encountered in a professional capacity in Python where optional type hinting was used but wasn't always accurate which was a special sort of hell.)
EDIT: the article even touches on this some in its description of Ruby: "Ruby is a language for programmers, and is at this point an sensible candidate for building something like Rails with - a relatively blank canvas for dynamic programming, with many of the same qualities as Perl, with less legacy cruft, and more modern niceties, like an integrated object system, exceptions, straightforward data structures." Ruby was newer, and wasn't something that grew out of sysadmin tools, but was always a full fledged OO application programming language first. So my disagreement with the article is that the culture then doesn't matter because no perl culture changes would've been able to reinvent the language as a nicer, newer language like Ruby because it never would've been perl anymore at that point.