If I had to slap down a guess on what is going on. The #1 issue is targeting cosmetic traits that are anatomically not functional. The #2 issue is breeders not prioritizing health over conforming to the breed standard. Pet grade purebreds may not look quite perfect to a discerning eye, but they can be very robust especially if they are a working dog.
If you control for #1 and #2 is there still a higher incidence of issues? Probably. Why would reducing diversity be a free lunch? Is it an ethical issue? Maybe. I mean I eat animals. I can't put myself on some high horse. At some point we make them to use so there is a balancing act going on.
The fallacy to watch out for is conflating breeder behavior and outcomes with outcomes for the breed if bred "properly."
Well I must say it is rare to see someone sliding down their own slippery slope, bravo.
Where working dogs are not status symbols, but a means to an end I agree there is market pressure. Assistance dogs in particular.
The focus on "sloped backs" among GSD breeders is a tragedy.
> If you control for #1 and #2 is there still a higher incidence of issues? Probably. Why would reducing diversity be a free lunch?
You just answered your own question. Is it theoretically possible for any species (including humans) to be purebred/inbred while still avoiding the whole host of genetic disorders and health complications? Sure, anything is possible. Is it likely? Of course not. The video does a pretty good job of showing how so many purebred dogs have worse health compared to their mutt counterparts.
You bring up a good point about eating meat. Most of us are willing to trade off animal welfare/suffering for human pleasure and aesthetics, so why not apply the same principle to dogs. One argument is that most people who adopt dogs do so with the genuine intention to love them and care for their welfare/health. In fact, people get so attached to their dogs that they spend a great deal of money to promote their health, and deeply mourn their suffering/death. Given this, it only makes sense for dog owners to adopt mutts.
Temperament is the most problematic because you can get a bad mix of drives and intelligence.
I think the question is whether what you get by picking the components is worth the cost? You won't answer that question with anecdata from a farcical comedy video. IMO the video does a lousy job of making any kind of useful point. I suppose it's good for awareness.
The video makes the exact mistake I warned about. You can't conflate what bad breeders do with what the outcome would be if all breeders were forced to conform to better standards or you find a breeder who breeds the way you want it done.
Straight from the video, breeders breed parents and children and siblings. It's sadly common that it will have happened at some point with many breeders. It's also insane and if you buy from a breeder that does that you have done something wrong.
If someone has some well thought out research comparing the outcomes of a known strong set of well bred dogs from a breed designed to be functional (for some definition) to a set of mixed dogs then we might have a way to quantify exactly what the cost is. Anything else is conjecture.
There are other strong arguments to be made for adoption and mixed breeds. Possibly for people unable to muster the expertise to find a breeder. I still think it's conjecture, but at least more reasonable sounding.
Some of those arguments apply to human breeding, but try having that conversation ;-)
If you want a purebred, adopt a rescue or buy one from a breeder that properly runs genetic clearances.
Where it is possible it will also be more effective than culling; it should lead to a population of animals that are free of the problem altogether.
For pups, we have a refund/buyback policy for animals that do manifest such conditions. We have on occasion "adopted back" dogs that the owner could no longer care for, and we've never had a problem finding them a new home.
We did acquire one dog that received an OFA "Fair" hip rating (as opposed to "Good" or "Excellent"), and she simply didn't breed. She lived a long and happy life among the rest of the pack.