I think you're mixing up "relying" with "providing data." My CPAP machine only doesn't track movement (I think) and def. doesn't track heart rate action.
All I'd like the watch to do is give me data I can analyze. I can then aggregate that data with things like activity levels during the day, and what I spent the night doing (How does Game of Thrones affect my sleep). I analyze data for a living, so I'm of the belief that there is no such thing as too many data points.
The thing with conditions is, unless you see your doctor every week, your going to have to track a lot of the data yourself. If I see my sleep doc once a year, and there is an app that tracks a years worth of sleep data (even if it's not as accurate as the home sleep study kit) she can combine with the data off my CPAP machine, that's good.
Also, I'm having bariatric surgery this year and hope to go off the CPAP machine. The sleep data off a watch would be nice to have to monitor that.
Interesting. Thanks for the explanation.