PBP is outdated and should only be used as a guide, not a bible. For instance, Conway was a big proponent of inside-out objects, but they are no longer in fashion.
Comment on Re: Why can't I find all of the Damian Conway Perl::Critic Policies?
Quote from Chapter 1 of PBP: "But remember that each of[sic] piece of advice is a guidline."
Changes in perl have made some of the advice obsolete. I believe that changes in fasion should be taken as warning when deciding wheteher or not accept the related advice.