Why modern warships carry only a few close-in systems

Why do modern warships carry only a few close-in weapon systems instead of dozens?

Cost and procurement choices limit the number of close-in mounts, just as they limit a ship's main-gun battery.

The answer is direct: decision-makers regard a much larger close-in weapon fit as too expensive. The comparison with single-barrel main guns places the issue within a wider pattern of procurement restraint. No preferred number of mounts or detailed cost breakdown is given. The watch point therefore establishes the stated budget explanation without extending it into an unsupported magazine or stockpile analysis.