First you claimed they weren’t useful. Now they’re simply inaccurate (somewhat valid, but see below) and when used stupidly can be privacy problems.
I can’t argue the latter, but that’s not just a smart watch problem.
Regarding accuracy, though, the Apple Watch is very accurate for heart rate, which is important because it can alert the wearer to dangerous heart conditions.
It’s also best-in-class accurate for calorie expenditure, which is fine for general day-to-day tracking and dietary planning.
>Overall, heart rate error was within the acceptable error range for the majority of task/device combinations, but EE error exceeded the allowed threshold for all tasks and devices.
And I repeat - for group level experiments such devices are good
There is the problem with hand devices and quality of measurements they do
Article describe it more properly
If you have heart problems and you need some measurements there are a lot of medical _calibrated_ devices for that
There are 0 devices for that which has only hand wearable part
Also consider such cases when such devices can do a lot of harm https://www.theguardian.com/world/2018/jan/28/fitness-tracki...
Any tech has pros and cons