> What is the purpose of show dogs ?
I assume you are talking from the perspective of dogs which have a sporting background - Function in the field.
Some utility,toy and working breeds either fully fullfil their original roles as companions or, as in the case of many working breeds, have no role in modern society.
Not much call for bull baiters in modern day Britain.
These breeds have evolved to keep the form but drop the funtion.
I'm sure there are many who feel only dogs who can perform a working role have a place in todays society - yet it is the dogs which best fit into a modern home and family that are truly successful as pets.
Working ( in the literal sense ) dogs are often too high drive for the average family and lack of stimulation causes behavioural problems and training difficulties.
A 'show -type' version of the cocker for example is often an easier pet to live with than it's working bred cousin.
Dog showing is perhaps a modern day 'field' sport for domestic pets. Not everyone either has the time or inclination to shoot.
For all the criticism of pedigree dogs lately it has to be accepted that dogs are one of the most successful species on the planet - they seem to be achieving this by fitting in where ever they are.
You want them to work - they will,
want them to sit on your sofa and play with your kids - they will.
Dog shows are perhaps the modern day field sport - not everyone has the facilities, inclination or ability to shoot or track or hunt.