I have always wondered about the purpose of smurfing. Infact, in a game with such "high level pros" and also so few pros (as they say) smurfing should be forbidden to good players: it's just a way to cover one's true identity to get an advantage. Mostly, I see it used as a tool to get revenge and/or to devise counters to strategies of players who beat someone who didn't like being beaten.
Of course, as things go, it will be always a widespread habit in all games which allow it. No reason not to say it's a bad habit, though.