Defacto-standards get applied as blanket requirements by PHBs, weak coders who want someone else to make their decisions and obsessive-compulsive paranoid pedants that once bitten through lack of knowledge or care, become twice shy about using their own faculties.
But what about folk like me who find tools like Perl::Critic useful aids in approaching lumps of bad legacy code, who are (hopefully) bright enough to realise that a code smell is just a smell and not necessarily evil in all cases. Who can read through PBP and agree with some things and disagree with others.
Are we supposed to throw away useful tools like Perl::Critic because some idiots misuse them?
In this particular instance it's been my experience - which obviously differs from yours - that people are always throwing unclean user input into single-string calls to system. I'd love a tool that helps me find these instances more quickly.