Yes, and that’s it’s purpose as of now. Since it also costs no energy to duel, gaining rewards would lead to farming exp. Right now it serves as a fun way to train besides the training dummies and to test other players fighters.
If you’re looking at it from time spent to pay-off, yes it doesn’t do anything and you don’t gain anything. Like my point was, it’s for fun as you can fight other players and mess around now that you can change who’ll be your defense. Maybe they’ll expand on it later on but as of now, it’s just there.