That's an entirely unrealistic stance.
Random dogs are not going to fit everyone's family and home. Adoption is awesome, and in my entire life, I've only had one pet of any kind that wasn't either adopted, a stray, or from "excess" litters of smal animals like rats.
But a lot of the reason dogs end up in rescues is the people being idiots about it. They get dogs as toys and throw them away when inconvenient. This does not stop just because the dog is adopted. Since shelter dogs end up being rehomed a lot anyway, they also end up older and with behavioral problems that make them harder to forever home.
Back when I volunteered in such things, the ones that ended up put down the most were puppy mill dogs. I don't think that could have changed much since then, though it is possible.
Good breeders don't fuck around. They will not sell a pet dog without a guarantee they get fixed. They have their shots up to date, and usually have well documented health checks for generations. That is more likely to result in a permanent home for the dog than adopting.
I dunno, maybe you've never seen how bad it can get.