It's just the language, and culture doesn't make it particularly easy
You provide no evidence (not even anecdotal evidence, just some innuendo) to support your claim.

• Language portion of your assertion is fairly easy to define, perl code.
• The Culture of a programming language is a little harder to define. I propose an applicable definition of "culture" in relation to a programming language: the sum total of ways built up by human beings and transmitted from an experienced group to an inexperienced group in a community. I think some acceptable examples of community would be Perlmonks.org and c.l.p.m.. I'm sure you come up with others. Since it far easier to (at least loosely) quantify experience at perlmonks.org I would suggest you start there (here). Saints in our Book should be a good marker of experience. Culture could then be quantified by the responses given by experienced members of a community to inexperienced.
• By 'it', in your claim, you mean 'maintainability'. Still hard to quantify but could be done. You could come up with a set of standards. Post an RFC and you would most likely get some good help.

It should be fairly easy to get a wealth of coding examples and answers from perlmonks. Then I would bet (a sixer of Rouge Dead Guy Ale, to be specific) if you examined this data and scored maintainability, you would find perl culture and language tends toward highly maintainable.