who were breeding for the right reasons
But what ARE the 'right reasons'?
Health? Yes, of course, but that doesn't mean that every dog being bred needs to have every health test going for the breed. A recessive is a recessive: great if the puppies are clear by descent, but a carrier of a simple recessive is going to be fine.
Temperament? Yes, of course, but that varies wildly with the purpose of the dogs being bred. One of my own dogs would be hell on legs in the wrong home, manic, loud and away over the horizon chasing anything that moved. In this home, she's just about perfect.
And beyond that?
'Betterment of the breed'? That way lies - if breeders are not exceptionally careful - an excessive focus on the breed standard and a dangerous narrowing of the gene pool (this is less of an issue in working dogs, where morphological extremes just bugger up a dog's ability to put in a day's work. Being bred for work doesn't save them from the inbreeding-related health issues, like rampant cancer, though: I'll never have a flatcoat for an assortment of reasons, but one of them is the cancer bomb tendency of the breed. When you've heard an about-to-be-bereaved owner talking, you don't forget it).
'To keep a puppy to continue their line'. What, every single litter? Even if they want their bitch to have her first litter now because she's already almost five, but aren't in a good position to keep a puppy and bring it on this year but should be in two year's time when they hope to breed the bitch again, and know that they'll have a queue for both litters, because they breed bloody good dogs... Or even if they already have two dogs (mother and daughter, and they had the grandmother) and want to wait a while before adding a third, but want that third to be of their own breeding because they very much like what they've got, and the bitch, as above, is already four, rising five...
IMHO, if your sole income is from breeding dogs, it is very, very, VERY unlikely that you are giving your dogs the sort of life I would want the dam of my puppy to have. You will have to have too many dogs to give them the attention they need. But if you net a few grand at the end of the intense and exhausting work of breeding and rearing a litter, I'm not expecting you to donate it to rescue, or sit on a spike, or feel terrible about it. I'm pretty sure the breeder of my younger dog banked a bit when he gave the last puppy to its new home, and good for him: he bred and raised a litter of healthy, fit for purpose and temperamentally solid puppies; he checked out the new owners; he let me check him out and didn't object to the 101 questions I asked him; he clearly loved his dogs; he's kept in touch. Was he an all-singing-all-dancing A* breeder? No. Did he breed some great little dogs? He did indeed. (And that's not just me saying that: I have had people who trial their dogs compliment me on mine.)
Also, if you crossbreed you are not the devil. Provided you consider temperament and do you utmost to ensure it's good, health test appropriately and account for wider health issues (are both breeds cancer bombs? Or riddled with allergy issues? Hm, perhaps not...), don't breed the bitch more than two or three times, give the bitch (and the stud) a good life, rear the puppies with love and care, screen your puppy buyers properly, and sell with a solid contract ('if you need to rehome this dog, it comes back to me'), what's the problem?