There are lots and lots of families out there who only have 1 litter from a beloved family pet because they want the experience/their children to help raise the puppies etc etc. I’m not sure why that is less acceptable than people breeding for show or whatever (and breeders breeding for show is a closed shop when it comes to a normal family just wanting a dog).
Because as a general rule, those people don't do any genetic testing on the dogs and have no experience of breeding, raising a litter of puppies or starting socialisation properly. If you make mistakes socialising a young puppy, you can cause life-long issues with fear and aggression. It's a huge undertaking and not something to take on just because you "want the experience".
I also don't understand why anyone would risk purchasing a puppy from someone who doesn't know what they're doing and hasn't even done the most basic of checks on the parents.
Rescues won’t rehome to those with young kids so what choice is there?
They won't re-home to families with young kids for a good reason - because rescue dogs are hard work and it's even harder if you're also having to control small children at the same time.
A good breeder won't sell to families with small children for the same reason. Puppies are bloody hard work and nobody is entitled to own a dog - if you're being turned down by decent breeders AND rescues, there's probably a damn good reason for that and you should probably reconsider whether you're in the right position to own a dog, IMO.
I have no issues with breeders, btw, my own dog is from a breeder, but he did all the health checks, the genetic tests, got the dogs hip and elbow scored etc.