Since we're overly simplifying, there _are_ devices that can detect conditions that 5% of the population has _and_ have far fewer false positives - X-rays, CT scans, MRI. In the grand scheme amazing things, but no-one's calling them "miracle devices".
Perhaps, but you can't wear one on your wrist and you generally have to be quite sure something is wrong first.
What would be more likely to happen in that scenario, is that so many people would be seeking care that the 5% who were positive would be unlikely to even get the care they need.
Further, such an influx would have knock-on effects on unrelated patients, whose care would suffer due to the severe lack of resources.
This is all magnified if the resource is not a general practice physician, but a specialist.
If the healthcare system - paid healthcare system - can't handle a slow baseline increase in non-emergency visits, then something is seriously wrong with this picture.
Hypothetically, let's assume over a long period of time new devices are alerting users to possible medical conditions. Those appointments are paid for (I'm guessing). Will that money not fund more availability over time? The supply of doctors is not supposed to be fixed.
I really have distaste for those comments that attempt to mask ideology with a veneer of logic. You attempt to use a limiting case argument that actually proves the original comment's argument and then end with rhetoric about how the healthcare system is being flooded already. That may be true, but that isn't relevant to the utility of the apple watch in this scenario.