Indeed I agree. Calorie burn is also nearly impossible to understand perfectly as it's such a dynamic metric. If you burn 500 calories, that doesn't mean you lose the fat associated with 500 calories. If you train on a day when you're in a calorie deficit, the body can seemingly choose to burn some fat, or it can maintain weight, and pull that energy from other resources such as the immune system (which could be a very helpful thing with regards to lowering inflammation, cancer growth etc). I'm likely running in a slight deficit each day, but my weight and body fat levels are very stable. The body is very good at adapting in this way.
On the watch, I use it as a useful general measure of how active I've been, or the effort expended in a workout. That's a better way of looking at it, without getting too hung up counting calories.