Given that ships are expected to operate for months on their own, in other star systems with no way to communicate with home except by sending a ship, I would expect that any ship designed for extended patrols would be capable of dealing with a variety of emergencies.
Like temporarily dealing with extra crowding from rescuing the crew of a disabled ship, or temporarily providing power to another ship so they could shut down and repair their reactor, or refuel another ship, with enough fuel to get them to the nearest starbase or other facility.
Also, people are getting all fussy about interchangeable fuel between carriers and fighters and LACs when they swallow the notion that a captured 5 hs missile can be fired from a 5 hs launcher, regardless of whether said launcher is cylindrical, square, hexagonal or whatever. There are far more incompatible things that are used interchangeably, mostly because of the rule of FUN.
My two cents is have a 50 hs fighter system that has 5% of the capacity of a 500 hs system, for 20% of the cost. So it isn't NECESSARY to have the smaller system, but it allows a play style. A fighter tanker would be 1/4 as efficient as the larger system, but it could keep up with the fighter wing without increasing the signature of the fighter wing.