I don't know. That can be true, but at the same time my (IRL) dwarven deck can take just about whatever is thrown at it in terms of strategy, with the possible exception of a hardcore corruption deck. I have a friend with a dwarven deck that is similarly strong, but made different (more event, token, and condition based). I also tend to see Rohan as a strong mono-culture deck. The remaining cultures seem meant to be dual-cultured, and that is what I encounter.