You will probably hear someone say that having the loose skin will help it to protect itself from bites, allow it to turn on something that is biting it and other things like that. I think, it was just an overexageration of characteristic as what happened with the Neapolitan Mastiff.  Some may think that if some wrinke is good then more wrinkle is better.. not true.  At some point the propensity for promoting any one characteristic of any dog will eventually cause phenotypical change.