We don’t see the rebel fleet in action until Jedi, and it does seem to be carrier-heavy.
As for the independently-operating fighters: they have to land somewhere, the pilots can’t just live in them and they need to fuel, receive maintenance, and re-arm. That’s either planetary (or equivalent) bases, or carriers, much like pacific WWII air operations were a mix of island airstrips and carriers (lots, and lots, of carriers).
That’s all for the original trilogy. What we have in addition, however, is a limited look at the inter-trilogy insurgencies and nascent rebel alliance, in a variety of movies and TV shows (e.g. Rebels). Those do seem fairly heavy on carriers, from what we get to see, plus light gunships.