Long distance targeting usually involves relaying target coordinates between sensor platforms like a destroyer and its chopper, a carrier strike group and awacs radar aircraft. Coordinate grids are used.
The less accurate is your determination of where you are in the grid, the less accurate is your targeting.
Launching a sea attack against a target 50nm away usually involves telling the harpoon/whatever what bearing to fly at and how long until homing radar goes active. You want to delay activating the homing radar as long as possible to avoid alerting your enemy.
So if your coordinates might be 10nm off vs 0.1nm off you might be forced to set your weapon to go active too soon, allowing your energy to shoot it down.
Modern sea-to-sea battles involve swarm of weapons, cause your typical high tech enemy has the means to shoot at least a few incoming missiles down.
So unless you're fighting within gun range, and alone, having something ideally that gives you accurate positioning within .1nm is very important, with many shades of gray all the way to dozens of nm errors.
Its not by chance that GPS is a FORCE MULTIPLIER. Having no GPS means your force looses effectiveness.