Well, breeding isn't rocket science. It's dog breeding. And anyone can be a dog breeder, whereas to be a rocket scientist takes years of school, talent, and a high level of intelligence. I would hate to offend any real rocket scientists.
Thank you for narrowing down the questions, what it looks like to me is, they are all pretty loose. And none are "professional". A "BYB" could "elevated" to "reputable" breeder with mentorship of someone considered (by whom is not clear) "responsible"?
If a "BYB" fills all other requirements but breeds only to their own males, are they still "BYB's"? How many qualifications need to be met before a "BYB" goes to responsible, or puppy mill to BYB?
I think Cindy said it quite plainly. What Cindy means (and correct me if I am wrong here) is that anyone, regardless of their past, can learn new things and change their ways. Meaning someone who was breeding in a way that would be widely accepted as unethical, or BYB, may potentially see the error of their ways and learn new things and breed in an ethical fashion.
The problem that I see with only breeding the males a breeder has to the females a breeder has is this: if your stock is limited (say you have two males and two females), you are likely not pairing the best male to your female and visa versa.
Here is an example (and these names are totally made up, I don't mean to draw a parallel to anyone on here)
Doug has two newf bitches and a stud. He bread his stud to both of his bitches in the past and they produced acceptable puppies that fit standard, but they were not 'show quality' (aka REALLY good) pups. Does Doug do the same mediocre breeding again? If he's looking simply to sell puppies, he might (this would be leaning towards BYB). If he is looking to better the breed by producing some really awesome newf pups (the dream for all ethical breeders), he would likely be looking around at either bitches that compliment his stud or studs to compliment one of his bitches, or both.
There is NOTHING simple about that combination... from what I understand it takes years to get the hang of it, and sometimes it comes down to trying out a breeding and seeing what happens. And it isn't something that everyone is good at (sort of like painting...some create a Picasso, others make stick people).
There are no hard and fast rules that govern the categories a breeder may get classified under, but if I can't walk into your kennel, meet your dogs, see pedigrees, championships, see copies of health clearances for both parents, a copy of your contract, get your club information, and your dogs don't look like the breed standard, I'm fairly certain you'd be in the 'less than ethical' category and I wouldn't want to get a puppy from you.