Since every ship has a primary weapon that is default equipped on the ship, and since the active modules on destroyers are essentially their primary weapons, I think that destroyers could use a “default” active module turret. When a module is not installed, a very low-damage PDT needs to be on the module slot to compensate. It should be weak enough to say “use actual modules” but strong enough to compensate for new destroyer pilots’ lack of active modules.
-Point Defense Turret
Damage: 310 kinetic
RoF: 240rpm
Range: 3,000m
Projectile speed: 8,500m/s
Recharge: 30s
Energy: 1,200pts
Tooltip: Passively fires a minigun at nearby enemies and drones. Activation increases damage by 25% and allows the turret to knock out 3 missiles.