I'd just like an opinion on this.
I know some people are just lazy and don't care to take the time to exercise their pets, but sometimes it isn't that simple.
Even if someone gets a pet with the best of intentions, and gives it plenty of time and exercise initially, sometimes people's lives change - illness and injuries can happen, the breakup of a family or downsizing or layoffs can prompt a reduction in income and a move to smaller living quarters, or may require the owner to find a different job with a longer commute or working hours. Any of those circumstances can drastically reduce the available time an owner has to exercise the dog. And of course illness or injury can make it impossible to take the dog running, and alternatives may be difficult to find or afford.
Should people in those circumstances get rid of their dogs, if they're no longer able to exercise them in an ideal manner? Good homes are scarce, and I doubt they'd be better off in a shelter kennel.
I'm not saying it's OK to let the dogs get fat, because diet can still be controlled- just that sometimes things happen and life keeps us from doing everything the way we want to or should.