Ok - I will do this one at a time. I agree with some of your statement but disagree with most.  I agree that Breed clubs are responsible for their breed's form, function and looks.  Your statement that breeding and showing do not change temperament or working abilities is subject to much more debate but I disagree. What I do know from experience and have seen and read and discussed with other dog fanciers is this - When a breed enters the major registries like the AKC and CKC they will be changed forever.  There are several breeds - lets stick with guardians - the if they are worth anything will never let a stranger put a hand on them let alone open their mouths and feel around at the genitals. You can see it happening with most of the rustic breeds today.  CO, CAO, Kangal, Anatolian, Neapolitan, Cane Corso, Presa Canario, Black Russian Terrier, German Shepherd - to name a few.  These breeds are no longer the breeds they were when they were "recognized" by a breed club.  Pick any breed you like and go back 50 years and observe the difference. 

Take the Neapolitan Mastiff for instance. The once venerable guardian dogs of the Italian country side the would scare the heck out of an intruder and provide an unstoppable frontal attack if needed. They were athletic and catlike, fearless, healthy, indomitable, fierce when guarding and loyal to their family - now they are only loyal to their family for the most part.  There are a handful of breeders who are actually trying to maintain the rusticity and athleticism of the breed - but for the most part the harsh temperament which enabled them to properly do their job and remain relevant is gone.

What took decades of centuries to develop into a breed can be ruined in a couple generations of show dogs. Yes, I have heard of people saying they take their dogs from the field and wash them and off to the show they go.  Ok, some people probably do that but not most.

About health issues - I remember when the Neo was accepted in the AKC and shortly there after the standard was changed to accentuate the breeds, big head, wrinkles, "massive" bone .. and a term called WHAM was coined by judges or others.. Wrinkles, Head, And Mass.. Lots of wrinkles, huge head and Much Mass.. 10 years later the dogs could barely walk around the ring let alone do their job and most of them could not see because of the wrinkles.. they also could not breed properly because their equipment was so far away from where it was supposed to be that the male could not find it.. if the male was healthy enough to mount her. Most Neos are bred today by artificial insemination. 

Ok, I fully agree that it is the parent breed club's responsibility to police their breed and protect its health and longevity.. they for, the most part, fail miserably.