And, dollar cost of the fuel is not the only cost of maintaining a "long supply tail." There's also the dollar cost of all the ships and sailors on that tail, and there's the logistical opportunity costs: we have to protect that tail with military resources that might otherwise have gone to more directly military purposes, and the head of the tail (the military activity at the front) is held back and slowed down by a "heavier" supply tail.

This doesn't eliminate the tail (we still have to deliver ammunition, lubricating oil, food etc. to the fleet) and it doesn't eliminate replenishment at sea (we still have to get that stuff from supply vehicles to ships), but it does lighten the supply load and create more military options.