Excellent point. For the same reason, Ruby/Rails is worth mentioning too. The article does mention Ruby, but not Rails.
The most interesting counterfactual is “What if someone had written something like Rails for Perl before 2005?” It was definitely technically possible, and it might have made Perl take back off (Ruby usage grew from basically nothing due to Rails), but the community’s focus on Perl 6 at the time made it much less likely.
Catalyst was released in 2005 (so still after Rails), and definitely didn’t provide Rails-like productivity.
If Mojolicious had been available in ~2003 or earlier, it’s entirely possible Ruby never takes off, because developers could get similar productivity in a more “known”/“mainstream” language.