Sure, it works, but their point is that the savings would be near exponential. Eg, a battery with similar characteristics but double the density might allow you to reduce the size of the battery by something like 70% while keeping the same amount of range. So the amount of resources required is greatly reduced. Considering it's only a matter of years before ICEs are flat out banned in most countries, figuring out more efficient ways to use resources for vehicles is pretty important.