Sure, there are the fancy fowl within the duck group (just as there are with chickens) where looks are the endgame, but there are also breeds of domestic waterfowl that can and do exceed the capabilities of chickens in terms of working livestock.
Campbells and Indian runner ducks are a case in point. Over the years they have been used as the primary laying breed within waterfowl and they are incredibly productive, producing 250-300 eggs in a season, which outstrips some of the best layer breeds of chicken. …"
From a comment by Anonymous