in reply to Philosophy for when not to support older versions of perl
this is often about bloating the code, affecting efficiency (AKA speed) and weighting all this.
I am always against pollutions of perl documentation with phrases like "starting with version 5.6 this function does this and that", which is - unfortunately - not a seldom in our perl documentation.
officially perl supports this and previous releases, but in practice this is a bit different
In Section Meditations