This same situation can happen within a house, as well.
The likelihood of someone wandering in your house and into your dogs bedroom, crate, whatever, is a lot less than your yard. Unless you don't believe in doors with locks?
I'm kind of surprised the only option people can imagine is a shelter-like boarding kennel. You know today boarding kennels can offer so much more. My mom and dad recently left town and boarded their 3 dogs in a "private suite", it was a locked room with a couch, a tv, it's own outside grass run, a kiddy pool, and running water for drinking. This was shockingly no more expensive than where I have boarded with my vet. There are also small operations such as in home care and in-their home care, like what my coworker offers, basically cage free boarding at her home (which may not be an option for a DA dog).
Sterile, traditional, boarding kennels have their place, I like their strut schedules and security protocol, but they're by no means the only option if you do your research properly.
Lastly, No one has claimed chaining or tethering is wrong nor do they make dogs aggressive. They do however not structurally protect against wandering children (hello media), adults, and even authorities cutting through yards for one reason or another. I remember in 2010 we had something like 6 different dogs in yards shot by our police force chasing suspects through yards when the dogs merely did what dogs do best. Freak events or not it's just not worth losing my dogs over.