The reason they do this is that their algorithm makes errors, and setting it this way means they can tune for a high specificity (giving up some sensitivity).

The reason they do this is that their algorithm makes errors, and setting it this way means they can tune for a high specificity (giving up some sensitivity). The breathing disturbances notifications work in a similar way. They alert you to potential sleep apnea, but then you need to do an at-home or in-lab sleep study in order to get a diagnosis.