I would not necessarily agree that Star Fleet Command did not ever use fighter-type weapons in space.
However, I would agree mostly with this quote:
There's little advantage when mass and inertia are not a factor due to dampers and artificial gravity technology. There's no reason a capital ship should be significantly slower or less manoeuverable.
I can see some use in sending a powerful one or two seater ship to tie up larger enemy assets with little expenditure of manpower, and presumably small ships are easier to manufacture in quantity.
It's more complex than current thinking of small/fast vs large/powerful.
For a fighter-type weapon to operate successfully in space; that is to accomplish its purpose of attacking the enemy, engineers would have to maximize its combat advantages over other types of vessels at the expense of all other types of advantages.
One obvious advantage would be to reduce unnecessary size and mass; that is any volume and mass that does not enhance but rather detracts from combat performance. That does not mean that fighter-type weapons would need to be small in size and mass. It just means that they would be smaller and less massive than they would be if they were also equipped with unnecessary things that would detract from their only purpose.
Constructing a very large combat vessel solely for the purpose of combat, however, would seem to go against Star Fleet design philosophy. While there could be political reasons for this, there are more likely practical, tactical reasons for not doing this. For example, size matters when it comes to targetting and evading. Concentrating resources by constructing a single very large weapon would invite a concentrated attack. Constructing numerous smaller weapons would have a marked increase in survivability and still possess the ability to jointly concentrate thier attack potential to a single target. In addition, it seems to be a long-standing philosophy that Star Fleet vessels must support a crew with its mandate to explore, help others, police borders, etc., effectively trading away combat effectiveness for other types of advantages that do not appear in fighter-type weapons.
Starships like the U.S.S. Enterprise are full of unnecessary—for combat—space and mass in order to make long periods of time in space bearable for a crew: things such as bedrooms, toilets, lounges, kitchens, machine shops, cargo bays, etc.—things that you would never find on a true fighter-type weapon. Of course, the Enterprise has energy and combat systems too, in order to defend itself and its crew, but it has the added disadvantages of increased size and mass relative to its own energy and combat systems. As a result, even when optimized for combat at Red Alert, the Enterprise could hardly be considered a true fighter-type weapon system.
Another unnecessary thing for a true fighter-type weapon is a pilot and/or crew that sits in the weapon itself. The best fighter-type weapons that would have truly maximized their attack potential would not require a pilot to physically accompany the fighter. They could be operated remotely or even independently. It would be quite arrogant of us to believe that a human pilot physically present in a fighter could do better than Star Trek computers, such as the old M-5 multitronic system.
Considering the design philosophies above, we could safely argue that Star Fleet Command certainly has used “starfighters” almost from its beginning.
They were called photon torpedoes.