Why shore bombardment needs dedicated fire control

Why did shore-bombardment ships need bombardment computers instead of setting the enemy speed to zero in naval fire-control systems?

Because the firing ship still moves and the solution depends on relative movement, geometry, and range rather than target speed alone.

Naval fire control depends on relative movement and range. A fixed shore target still leaves the firing ship in motion, and the solution must account for changing range and three-dimensional geometry. Setting the target's speed to zero does not turn the problem into ordinary ship-to-ship fire control. Dedicated computation translates the geometry of a moving gun platform and fixed land target into an accurate solution.