I think it depends on what the person does with their dogs. for example if a person just has dogs for pets, then I agreethat there are very few exuses for rehoming, but valid reasons DO exist.

the the person has working dogs however its a completly differnt story, there are people who rely on dogs for their livelihood, for example a sheep or cattle ranch, not a small hobby one, but a real working one where the rancher makes his/her living from the operation. those dogs are working animals, they are sometimes pets too, but they are working animals FIRST. if they cant do the work required of them, or "earn their keep" then they cannot stay, simple as that. the owner is out in the feild all day with the dogs that can do the work, that leaves the incaple dogs sitting inside a kennel neglected from dawn to dusk. these people cannot "make time" when their work day is 12 hours long. now that said there ARE farm FAMILIES that keep retired or otherwise incaple dogs as pets, but these are families or couples, NOT single ranchers.

then there are serious sporting homes. I am not refering to homes that get their pets involved in sports,or hobby breeders.I am refering to homes who get their dogs FOR sports. be it sleddogs, flyball, racing or conformation. these are homes with people who travel virtually every weekend for trials and races and shows, and during the weekdays they practice for trials and races and shows. if a dog cant cut it for whatever it is the owner does with the dogs, then that dog just winds up left behind, practicly living with strangers hired to come watch that dog during shows. curing pratice and prep times they are left again because the owner needs to focas on the dogs that are actually racing or showing. if the dog isnt up to snuff then they should be rehomed with someone more suitable to the dog, that can give them the time they need.