It's not a dumb question at all... but I doubt you will get total agreement on what is needed. Many, many people feed hay as well as whatever concentrate they prefer (fodder, pellets, grain).
It provides ample fibre for the rabbits' digestive tract and bulk so the rabbit feels satisfied.
It gives the rabbits something to nibble throughout the day, which is the way rabbits feed in the wild. A bite or two of this plant, a nibble of that... a few hops and another nibble.
If a pelletless diet is being fed, alfalfa or clover hay is important as a source of protein. Fodder can fill this need as well, however. At this point, we lack information on how rabbits on fodder prosper over time. It's a relatively new concept for rabbits to be fed substantial amounts of fodder as a main ingredient in their diet.
I personally prefer to feed a variety of foods: alfalfa hay, some grass hay, small amounts of grain, and as many gathered greens (mainly weeds) as the season and our time permit. In winter, root crops and other vegetables, pumpkin, occasional apples etc. make up the fresh foods. Late last winter we experimented with fodder and it should provide our rabbits and poultry (a goose and chickens) with a good fresh component this coming winter. The rabbits always have a trace mineral salt block as well.