The popularity of Perl coincides with the golden age of personal computing (and hackers culture). PCs got powerful enough that individuals could do the same things that were only available to big corporations and sometimes universities. Perl helped to harness this power, becoming the proverbial "Internet duct tape" to connect things (in the world of UNIX with emphasis on text protocols, the most powerful language for text processing won).
When lone hackers were no longer enough to satisfy the demand, the world had moved on to create _software industry_, and Perl's advantages (all power to the individual) started to be harmful. Different individuals have different preferences, and when you have to work in the team, reconciling your differences with your colleagues creates way too much friction. To facilitate teamwork, more uniform languages were deemed necessary, where understanding other people's code became a priority. Even open source software moves faster when anybody can read and participate in your code without fighting over style. This attitude was firstly exemplified with Java; now, we have Golang, which is a king of all languages optimized for team development. To facilitate this, the expression power available for individual developers had to be cut short.
As a consultant supporting my own code, I still use Perl, and if you are working alone, it's your fine bet. But as 99.9% of people work in teams, Perl6 is not the best choice for them.