Maybe70, I am not saying breeders who exhibit their dogs are unkind in any way, most, I’m sure, are exemplary dog-owners who love their dogs and want the best for them and their puppies. (Not the case with puppy farmers)
I am comparing conditions in breeding kennels, where un-neutered dogs of both sexes have to be kept separately at times for obvious reasons, requiring facilities, often kennels, for doing so, with dogs kept in the home as pets, where segregation is difficult, or nuisance behaviour hard to manage. In those circumstances castration could be a sensible option.
My comment above is a response to David49’s reference to the behaviour of dogs at Crufts.
Another point David - in-season bitches aren’t usually exhibited at dog-shows, so entire male dogs aren’t put to the test.