Are you suggesting we wouldn't have the "modern testing culture" if there hadn't been a Perl 6?

No. I meant exactly what I wrote. The testing culture Perl has now is due to Perl 6. The Perl QA group began life as the Perl 6 QA group.

Even if I did have a time machine and the power to create parallel universes, I have no interest in running the kind of experiments necessary to prove that Perl 5 would have eventually stumbled into something equally good (if different) or better without the existence of Perl 6. You're welcome to speculate as much as you want, but it doesn't matter.

It's foolish to pretend that Perl 5 hasn't borrowed liberally from Perl 6, from simple features such as say to larger features such as Moose (though Perl 6 isn't the only influence there) and smart match, and even to development practices.