Watching the interviews in the BBC documentary linked above, it looks like a complete mental disconnect with show level breeders. Too much prestige, ego and money on the line, and they are in flat-out denial.
Plus an additional answer, demonstrated by the bleach blonde breeder of champion CKC spaniels that have skulls too small to contain their brain size (1 in 5 have nightmarish agony); she does not care that the dogs suffer for these standards of "beauty"....which is almost too monstrous to contemplate.
As much progress as has been made in anti cruelty law, I think it might come down to making extreme inbreeding illegal, for a start.