Even stepping away from the BYB argument OP, the main consideration here is WHY you want to breed, knowing that it will allmost certainly be in some way detrimental to your bitch's health. Even if all goes well, pregnancy takes a huge physiological toll on any animal, and there is no benefit to that animal.
In the last few months my experiences with breeding bitches have included:
2 C-sections- one with live puppies (minus one) and the other sadly with none, in that case the bitch was lucky to survive and needed a hysterectomy.
Puppies with cleft palate that had to be euthanased at a few days old (from an experienced and concientious breeder)
A litter of 6 pups that died one by one, breaking the owners hearts (one survived)
A lovely home-bred puppy that died under the anaesthetic to try to fix a congenital problem 
A litter where two of the pups, whose owners were delighted with them at 1st vaccine, have been passed on to someone else within weeks
A litter where the dad, albeit lovely, had entropion (an eye abnormality) and subsequently also turned out to have a (possibly congenital) endocrine imbalance, and who died befor he was even 3- here's hoping HE hasn't passed anything on to those pups.
Add to that the number of false pregnancies (distressing for bitch and owner) and emergency ovariohysterectomies due to life-threatening womb infection and you possibly begin to understand why I personally would never put my bitch through it, and had her spayed early on.
It's easy to say it won't happen to you, but it happens to many. Most people mean well, they really do, but they aren't knowledgeable enough or aware enough, and feel terrible when it all goes wrong. That's why I would try to deter anyone from breeding unless they really have the future of the breed as their core reason for taking those risks.