I used to think this way, but changed after playing with a group that had a 2hd dog at level one. We often went out of our way to protect it. This was especially true as we got to higher levels. Buffs that gave temporary hit points were a must, as well as the DM allowing death saves. There were times we kept it at our base (a brewery/space to live) when we thought it was too dangerous. And there were times we made it invisible (our ranger had trained it to sit and stay quiet in dangerous situations). Our DM sometimes made the dog make a con save to sit and stay quiet. Also, that dog was healed more by our cleric than our fighter was.
For our group, it drained resources. But we cared about that dog, so we didn't mind the resource drain.