What the vim movements do is allow you to focus on your code without interruption. You can do everything without shifting your focus from the block of code you're currently editing. It's hard to describe until you've experienced it. I think it's just easier to get into and maintain a flow when the editor gets out of your way.
Our experiences differ with regards to the correlation. In my career I've seen a massive discrepancy between effectiveness of editor use and developer impact. Off the top of my head, save for one person (who used Sublime), every outstanding engineer I've worked with have either used vim or emacs.