I've read other posts on places like Quora or Reddit about how ineffective lasers would be as anti personal or anti ship weaponry, but what about for point defense? We see cases in the story of the PDCs running out of ammo/jamming/other mechanical failures. Theoretically, lasers would be less prone to such issues as there are fewer moving parts, right? Contemporary militaries have (sea/air) ship mounted lasers to destroy or jam incoming missiles, so why wouldn't this work in space?
I understand people or ships could have ablative armor but would that be practical on a missile?
PDLs would not be subject to running out of ammo, and if ships can power railguns they should be able to provide ample power for lasers capable of slagging or jamming incoming missiles.
Great question! I'm not sure of a good answer though, maybe try emailing the authors to ask?
Rocinante had a separate bank of batteries/capacitors for its railgun. That had to add a fair amount of weight, which reduces maneuverability. Sure, the drives they use are hand waving magic future tech, but a ship the size of the Rocinante might not be able to power 6 lasers.
There's also the durability of the PDCs to consider: if the heavy duty power cabling is damaged, lasers can't fire, but a PDC just needs minimal gimbal power and a control circuit. PDLs need a lot more stuff that might not be very tough, like capacitor banks.
Plus PDCs can load different ammunition. Flak for missiles, armour piercing for ships.
Or it could just be an oversight by the authors! I'm not sure if any of my reasons are valid, it could be anything really.
Don't forget heat! In space you can't dump heat into the atmosphere, so PDLs would not be able to support as much of a continuous firing rate as PDCs.
Also PDCs can be used to lay down a flak screen, potentially intercepting additional missiles.