I hate thinking of this as RP vs. Powerlevers. Many good rpers powerlevel at some time. In fact nearly everyone does it at some point, to some extent. I define it as training yourself hours on end, neglecting virtually everything else. Yes, mine is a universal viewpoint, but again, I don't think of it as a conflict of interests. Just as a temporary mode of playing. If that's all you do, you're still in the same catagory, just at the most extreme of it.
In other words, if you eat hamburgers, you are a hamburger eater. If you eat them every day, you are still a hamburger eater. Mmm, hamburgers...