... certainly doesn't justify (in my mind) requiring the use of 5.10 as a minimum version in a CPAN module.
But it must be borne in mind that there can be considerable time and expense involved for a company to (run a reasonably recent version of Perl)...
You want CPAN authors who give away their code for free, largely in their volunteer time, to test their code against at least a dozen and sometimes as many as seventeen or eighteen stable releases because it's too expensive for a business to upgrade to a supported version of Perl? You object to me using features I personally added to Perl itself several years ago in my CPAN code because it's too expensive for your business to install a new version of Perl more often than once every five years?
I can understand why you might want that, but why would I do that?