Not sure of the point.

So I have a difficult time doing/practicing things if I don't understand the why. That being said: Gesture? I'm seeing/reading people talking about it being used to catch the lines of action, the rhythm, flow, etc. But then I see the characters drawn using said gestures and I just don't see the point. I feel like it's something that's a separate discipline. Sure, it could be used to help create a baseline sense of movement in a finished work. But I'm having a tough time seeing how that translates from gesture to finished work. Or even structural/construction work.