Why are some ski bindings no longer supported by the manufacturer - cannot get mine adjusted by a technician - for legal reasons - After just 5 years you must buy new ones?

The manufacturers stop supporting them after a few years (sometimes earlier for certain models) because they start to fail. They're afraid of getting sued by the user if they get hurt. Likewise the technician is not allowed to adjust them, because the manufacturer has stopped covering them, so they're afraid of getting sued as well.