I'm sure none of us are losing sleep over this issue, either, unless our personal business ethics are being called into question. I believe that most of us here would never consider killing healthy animals in this way and I believe that most of us would not knowingly do business with someone who would.
That being said, it would be really easy to inadvertently drag someone's name through the mud with accusations or insinuations so unless you've actually witnessed a breeder killing off healthy offspring or a breeder has told you directly that s/he does so I would be very hesitant to say that you (general you, not you you) know a big breeder or breeders who do so.