Close up of an iron strike with divot taken with Phantom slow motion camera.
Slow motion close up of the line drill. The aim is to have the bottom of the arc after the ball every time.
On a basic level of bat and ball skills, swing path is a fairly instinctive dynamic of ball striking. It is also a major effector (along with clubface and angle of approach) on ball direction and curve.
This is partly why golf is so difficult to learn. Instinctively, a sportsman would lean back and scoop underneath a ball to project in the air. Try that in golf and we only top it along the ground.
This really is a fundamental principle; the understanding of which will greatly influence the development of your swing.
This is integral to solid ball striking. The brain needs to know the intended body shape and shaft alignment for powerful ball striking.