Additionally coming home and having someone who's happy to see you helps forget about all the work-induced stress.
If not, you have a study showing that 'Dog ownership promotes regular healthy walking'.
That’s a factor, but a few studies have shown association with a dog in a household (not ownership) has positive effect.
Companionship is a key factor with dogs and a key deficiency in many people. The human-dog relationship is unique because we snap into the dogs innate pack structure. Dogs want to take care of us, and that brings joy.
I’ve seen it with elderly folks and my own son. Our family dog made herself my son’s training wheels when he was learning to walk.
[1] I vehemently believe in the "80% thinking, 10% cooding, 10% testing" idea of software development.
You have a wildly optimistic view of the average dog owner's level of responsibility and proactive care.
They also tend to pester you for food or walks roughly at the same times every day, so, no matter how irregular your lifestyle was, there suddenly is a wireless alarm clock all day. Every single day. (Kids are much better at this, though).
In the EU and US at least, you can get this all for free: Sign up as a volunteer at the next animal shelter, commit to walking one of their dogs twice a day, 7 days a week :)