The purpose of carriers is to provide a mobile landing ground for planes on water (or in space in Disco). That is because planes often don't have enough fuel to travel, let's say, from Pearl Harbor to Midway. Today's planes might even make the flight, but sending them from Pearl Harbor each time you want them to reach Midway consumes a lot of time, so you had better have a mobile landing ground bring the whole stock closer to Midway.
In Discovery, all ships have infinite fuel and carriers can't be used as in the latter description because you are not supposed to F1 in space (and as I know, that returns your docked snubs to the last base they were docked in). Additionally, a travel from one spot in your average ZOI to the furthest from it usually doesn't take longer than 15 minutes, so snubs are very able to reach the place of battle quickly from any stationary base.