I hand-waived over Perl regexes not being entirely regular. They are still not (without doing really convoluted things) a Turing complete language. Matching the complement of the text that's bracketed is still a step beyond matching bracketed text. Just because one can hammer a screw does not make a hammer a screwdriver nor a screw a nail.
I remember a time when helping people with questions that this community would actually try to offer advice on good, clean ways to do things. I'm unsure of the value of arguing that because something is strictly possible that we should help do things the wrong way.