My current breed is a Welsh Terrier, and I’ve been told that is pretty common in terriers for the dog to live with its handler while being campaigned. A lot of it has to do with the need for regular grooming, esp. in the wire-coated terrier breeds that need to be hand-stripped at specific intervals so they can stay show-ring ready. Not many “amateur” terrier owners know how to do that kind of stripping, or have the time or inclination to do it on a regular basis.
And like in many other breeds, a lot of breeders/owners of “show” terriers try to place their dogs in pet homes after their show and breeding careers are over. That can certainly be a win-win-win for all concerned. In our case, we got a lovely, well-bred, AKC champion bitch (who also happened to be crate-trained - a big plus!). The bitch got a loving home where she is well-cared for and doted on by people who adore her. And the breeder/owner got one of his homebreds placed in a good home, which made room for him to keep one of her daughters to carry on her bloodline.