Way to get me to agree with you.
You do
have to agree, however - because you do, evidently. Both of those are entirely reasonable assumptions.
Anyways, the former is a pretty damn good reason AGAINST fighters and the second is oretty much unrelated to this whole issue. I don't see how they lead to your idea of fighters being useful.
Which means you essentially didn't read the whole thing properly. I did explain why the ships being valuable gives rise to PD and counter-PD weapons. If they weren't, the name of the game would be ship-busting weapons, and attacks to destroy rather than capture. Mobile, low-power weapons would mean nothing, as they would not be targeted first, except as a means to get a clear shot at the enemy with a few big guns. Holding weapons in reserve would be meaningless. Missiles would be doubly meaningless with their travel times. PD would exist as a secondary mode of operation for primary weapons, and as a means to quicker destroy enemy lifeboats, and would only see combat use in the rarest of cases. It'd be an entirely different evolution path, so to speak.
I also just noticed something about your argument...
You never actually explain why the magtanks wouldn't work.
They wouldn't work for the same reason a NASCAR stock car is wouldn't work for the bi-annual Russian Rural Rally Cross Championship. Think of how fast a turret like that would need to go, using the smooth surface of the armor to attach itself firmly and not accidentally fly off when there's a curve or the ship lurches suddenly. Think of what would happen if it hits a strip of armor melted by a laser beam at speed. Depending on how its magnets work and how fast it was going, it might become the inspiration for the detachable drones.
In other words, where rail turrets can be boxed in by destroying their rails, magtank turrets can be boxed in by simply shooting up the ship hull around them. Not a perfect weapon by far.
And again, your "evolution" path requires a specific line of steps, of jumps in ideas, which I just don't see as being the likeliest or most logical ones. Most importantly, you are taking the idea of "mobile weapons become new paradigm" to unreasonable levels, where the mobility of the weapons reach a point where increasing it costs more than it's worth.
I don't think these levels are unreasonable. The jumps of ideas I see are logical - to me, at least, obviously. How would
you propose the weapons and tactics to evolve given the initial conditions? I have only outlined one of the possible paths I see - but no matter which path I see, in those conditions all of them lead to the appearance of mobile weapons. Be it as a weapon meant to hide or as a weapon meant to ambush after a supposed defeat, but they appear. I'd be interested in a counter-take.
A fighter takes a LOT more resources to make and support than a railturret or a magtank or something, for one, and being silhouetted against the non-metal depths of space (as well as a hell of a lot larger), plus their reliance on their limited reaction mass, makes them easier to hit...which counteracts the whole point of mobility.
Again, limited reaction mass. That is really only true for the modern rockets. In the case of a mobile weapon, using the same powerplant to feed the weapon and the engines, interchangeably, you could have more delta-V than whole heavy lift vehicles - with, say, fusion engines. Like the one Simus is currently trying to turn into a missile warhead in VR. Support? They're unlikely to need repairs, have self-sufficient power, and only need to be topped up on fusion fuel every now and then. Maintenance? If they return from an engagement they only need a refuel and a checkup - at all other times they are dormant and don't have moving parts that could wear out or need replacement. They can EVA themselves into a hangar or a drydock. Replacing them is a trivial matter. They incur far less logistical expense than ship-based mobile weapons, the use of which requires constant repairs and drydock time - this alone might be enough to offset their cost.
Again, I can't accurately project that far out, so I'm reaching for specifics. The core of the idea still stands, though. Taken far enough, a war waged by ships too valuable to destroy will move the fighting away from the ships, one way or another.
What are you guys arguing about?
Nothing near tangentially relevant, I think. But it's fun! ^_^