Some class are really weak on 1v1, but under dominion they do have strengths to win the game indirectly
LB is a good example, it's one of the best minion cleaners. Always a good aid to the team if you have a LB who keeps minion zone in control, and assist contested zones from time to time with his CC.
And because of shove and revenge mode, he is the hardest to kill if the enemy team don't have a CCer, and that means LB alone needs 2 of the enemy team to kill.
And everyone knows how bad he is in 1v1, especially duel mode where the only purpose is to kill the other guy..