Same thing unfortunately with lasers: there are a ton of problems that make them impractical as main armaments.
The minimum dispersion of gaussian beams means that the emitting lenses need to be
big (think tens of meters) in order to focus energy onto a target. This not only takes lots of mass and surface area, but lenses are almost by definition fragile and every scratch/pit/nick on them degrades the weapon effectiveness severely. If the lens were slightly damaged and its absorption increased, it would explode.
The heat buildup of firing lasers that could cut through/blow up a ship would almost by definition be extremely hard to manage. Using disposable lasers where the heat is ejected in the disposable part very shortly after firing is a possible solution, but if you have a portable laser system such as a bomb pumped xray laser, that could most likely be mounted on a missile.
Finally, powerful lasers are somewhat easy to defeat: a cloud of absorptive gas and/or a wipple shield, not to mention armor designed to turn into a cloud of absorptive plasma on superheating, would all severely degrade energy transfer.
That said, lasers have the extreme benefit of speed of light travel, so they would be good in close range, lower powered applications: point defense vs incoming missiles.
For realism we have ships coming in, firing off Anime levels of missiles, shooting down enemy missiles, shooting lasers at each other, and massed hangar units dominating the skies. Between the fleets is a no-man's land of hangar units and missiles crisscrossed with lasers. Offensive ballistics would be the god weapons at close range that pierce through entire ships and run down a column of ships dealing massive damage.
So, Starsector doesn't make realistic sense. It doesn't need to. It is a game. The design of how combat and trading works has evolved to be more fun to play.
Oddly enough, you can do something that is an approximation of realism with Mora mono-fleets. They're insanely deadly. I've tried them with massed reapers. I just tested them with massed Pila, and they're taking down 5 star remnant fleets more easily than with torpedoes.
Gonna disagree on one thing here, fighters are not at all realistic without pulling some shenanigans in the rules of your setting. To quote tv tropes:
Spoiler
While there are advantages as well as disadvantages to space fighters when directly compared to larger ships, a good look at the concept from the very base upwards is necessary. The first question shouldn't be "What advantage does a fighter have over a big ship?" but "What can a space fighter do?" Because we're talking about military ships here, the answer is generally to bring some sort of weapon payload (bullets, lasers, blaster bolts, missiles, bombs) in contact with a target. But the conditions of combat in space make fighters pointless for that. On planet, fighters are needed to extend the range of whatever deploys them (an airforce base or a carrier). If the base were to shoot the guns or the missiles that a fighter carries directly, it wouldn't have nearly the range that a fighter can achieve. The horizon on planet prevents direct targeting beyond a limited range. The friction of the air slows down bullets and missiles so they drop to the ground short of the target when they have been slowed down enough or their fuel has run out respectively. The engines and shape of an fighter allow far more efficient travel in atmosphere than those of a missile (or bomb or bullet).
Not so in space. There is no horizon, so everything can be targeted directly. There is no friction, so ranges are not limited. There is no need for aerodynamic design, so missiles are far more effective than fighters. For comparison: if one were to use a missile that is the same size as the fighter i.e. using the same engine and same amount of fuel, it would have four times the range of a fighter, because the fighters needs a lot of fuel to brake and return to base again (and this is before you take into account the fact that using a missile instead of a fighter also frees up space that would be otherwise taken by the pilot and whatever equipment he needs to both stay alive and control his craft). So, unlike in an atmosphere, where mounting missiles on a fighter extends the effective range of the warheads, in space it would seriously limit it.
As for guns, those are even less effective. Unless there is some sort of magical technology at play that makes 5 tons of gun components, propellant and bullets somehow capable of more destruction than just 5 tons of warhead (not the case with real physics) then carrying a small gun close to a target to shoot it is a colossal waste of time.
Targeting is another thing that potentially looks like a reason for fighters to exist. But it is again not the case. Getting closer to the target does exactly the same thing as using a bigger lens (because there is no horizon) so the bigger lens wins. (It does not get closer to danger, doesn't need refuelling, etc.)
Intercepting incoming missiles works pretty much the same as launching attacking missiles, and attaching a space fighter makes it worse, not better. For that matter, anything that can destroy an incoming missile will probably be just as effective against a fighter, too.
In the end, while one can point out plenty of advantages that a space fighter has over a larger ship (in a universe with real physics), there just is no task that a space fighter is best suited to perform. Either a bigger ship will outperform several small fighters, or one or several missiles will outperform one fighter.
So if anything, the most realistic you can get in starsector is gryphon spam 
This is somewhat true, but the person writing that quote was unimaginative in terms of useful things for a drone to do and also got their physics wrong on a few things. Here are a few uses for drones/loitering missiles/reusable stages:
1) in mid flight (as opposed to terminal approach) evasive action a missile takes is wasted dV, so wasted range and less velocity when getting into firing range (so more time available for PD to shoot it down). So it would be beneficial to have small craft between the place where humans are mothership is and the place where the missiles are coming from, both to shoot the missiles down early but also to force them to evade and/or use countermeasures (defense in depth). The small craft does not need extreme dV itself: it just wants to get in the line of fire and stop, so it makes sense to have a reusable high efficiency engine and powerful/expensive targeting system rather than a throwaway system, if possible (though it wouldn't be manned). The armament of the small craft/drone could be anti-missile missiles, lasers, or something else, but it all benefits from a closer launcher/targeter.
2) active sensors. While undetectable stealth is impossible in space,
obscurement via ECM or other means is not: fooling the targeting sensors of missiles via various approaches would be critical to warfare! However, its really hard to obscure your ships when its blasting out radar waves (or whatever other active sensor emission). So put them on drones! But they are all expensive, so you want them to be recoverable if possible. Getting those drones to be spread out also helps.
3) passive sensors. The maximum resolution of a telescope/antenna is dictated by its diameter; however, that doesn't have to be filled diameter when multiple detectors are combined interferometrically. So launch drones with detectors on them and network it all together.
4) This one is more setting dependent: if different levels of engine tech have different delta V/thrust capabilities but are also different levels of expensive/size, then a recoverable 1st stage for primary missile armaments would be desirable.
For example, what if practical fusion torch engines are big and expensive? To me that would imply that a "missile" would be best built as a 2 stage device: a first stage fusion torch drone that accelerates the warheads, and then a second (multistage potentially) chemical rocket for each warhead that does final homing and approach, and then either does a contact detonation of fires a one use bomb pumped laser. The first stage fusion torch would have 2 modes of operation: long range, where it accelerates all the way to maximum speed before firing off the second stage: this would sacrifice the expensive fusion drive, but give better range and velocity. Or a mode where it releases the second stage at ~45% velocity, then come back to the mothership at ~10% velocity (with 45% spent stopping): this is lower performance but saves the first stage for later launches.
