It's probably similar to the difference between doing "proper" squats in a squat rack vs. using a cheater frame. The muscle movement is more varied and not as linear as doing a single left/right up/down exercise. But that's just a guess.
Is there any hard data on how much a machine impacts muscle growth/flexibility/whatever vs free weights?
I agree that free weights are probably better overall, but would love if that were quantified somehow.
isn’t it just about mind to muscle connection
The study is about a specific type of eye exercise. The translated English title makes it sounds more general than it is.
I don't think they know for sure what it is about being outdoors that helps prevent myopia. But it's thought that it might be the bright light. To me, passively taking in bright light wouldn't qualify as an exercise.