Add in that technology can measure certain things, like whether you hit the right notes, but can't measure other things, like whether:

1. your posture is terrible (shoulders, arms, etc.)

2. you are arching / lowering your wrists

3. you are humming to yourself while playing ala keith jarrett

4. you are using the correct fingerings

5. you are playing in a way that can be sustainable for hours a day (e.g. you can play poorly for 1 hour but not for 40 hours / week)