Matchmaking Support Article states Riot is working on a more positive system to Smurf
HOW DOES RIOT FEEL ABOUT SMURFS? Riot does not officially condemn or condone smurfing. We understand the cases where players make new accounts in order to help teach new players the game, but are working on newer systems to provide a similar experience in a more positive way.
I'm not sure how long that entry has been there, but would love to hear what ideas they've cooked up and if they're actively working on something or plan to.