Does a long-range gun need better accuracy to be useful?

Is there no point in a long-range gun if it cannot hit reliably?

Greater reach gives a navy reason to work on hitting at that distance; the gun still has value while that work continues.

A gun's ability to reach a distant target creates a reason to improve the means of hitting it. Greater reach directs further development effort towards accuracy. It does not make the weapon pointless while reliable hitting remains difficult.