chickentrains
love is love
I don’t know if it’s the same with dogs, but with chickens, sometimes breeds need to be added to a breeding line to improve traits of a breed, like Barred plymouth rocks getting added to improve the barring, and things like that. The first few crosses are mixes- yes. But after many generations they become pure. It’s the same with creating new colors within a breed. Most breeds are mixed at some point.
Its not the same with dogs. The merle isn't improving the breed at all. Its only adding more health issues. With Dogs, there was a breed standard written up years ago, and every dog produced should conform to that standard. Unlike with chickens, if the parents of a dog weren't registered, you cannot show them, and you cannot register them. So if a dog had two registered parents, but wasn't registered itself, then had a litter, that litter is not allowed to be registered.