The main functionality I want is notifications. If I don't install apps on my phone, I'm not getting notifications on my phone, and thus can't get them on my wrist.

Additionally, keeping health tracking turned off on the watch means that, in addition to not taking your pulse dozens of times per day, you can't engage in the normal workouts either. Each time I work out it's four steps: enable health tracking, start workout, end workout, end health tracking.