* it's a book for novice programmers, people with perhaps six months of practical programming experience
* it's a book for novice Perl programmers, people who don't have voluminous experience with the language itself
I believe programming is an exercise in making tradeoffs based on incomplete information. You can't teach the kind of good judgment that's based on experience, but I can try, at least, to guide novices away from some of the traps that they're likely to fall into. The subtleties of separate namespaces are difficult enough to learn on your own that it seemed worthwhile to advise strongly against name cognates.
I don't expect that Larry, Tom, Damian, or Randal follow my advice. I don't even follow it in my own code many times. It's not advice for experts.