Indeed, if you read The Goal or The Phoenix Project, they call this "slack". There is a whole theory about why slack matters.

Another way of looking at it is that fat serves a purpose in the body. It's true that if you're optimizing for a very narrow outcome, very low (but not no) fat bodies can look ideal, but for one thing, that's actually a pretty unhealthy body, and for another, the best weight lifters in the world actually have pretty substantial fat reserves to support and sustain their muscles.

No fat can help for going fast and efficient, but it prevents you from going strong.