> If someone is 'dog person' they have routine where they take dog for walks, with positive effects such as exercise, without having to weigh pros and cons each time it is performed.

That describes a dog owner which is a much more concrete category than "dog person". Not every "dog person" actually has a dog. Even if you want a dog, your apartment might not allow dogs, or you might not have time/money to care for a dog while working.