First, why should smurfing be minimized? There are a number of reasons, and while I won't go into all of them, below are few of the key ones:
1. Smurfing is the safe haven of trolls, the escape of ragers, and the return of unwanted elements. If Riot is serious that a permanent ban is a message that Riot does not want the player in the game in any capacity, then dealing with smurfing is of huge importance.
2. Smurfing devalues a player's primary account . The option to smurf makes the permanent ban a less terrifying threat, thus taking of its teeth. Don't get me wrong, a permaban sucks, it really really sucks, but it's not really "permanent."
3. Smurfing disrupts matchmaking. Matchmaking is honed over many games, and for a normal new player, Matchmaking makes a guess as to where that player belongs, and is more often than not, pretty close. The player's matchmaking rating moves slowly as their skill improves, but they are fairly consistently matched with similarly skilled players. However, a smurf throws this completely out of whack, as a smurf often has very few games but the skill of a player who is much more experienced.
I don't think there's a simple solution to to make smurfing impossible. However, it's certainly possible to decrease the rate of smurfing. One example of how this could be done:
1. As part of creating an account, require an upfront Fee of $40.
2. Provide an option to waive the fee if a mobile number is provided. (It is possible to verify a mobile number as a mobile number, not VOIP, and in fact there are services which do so.)
3. If the phone number waiver is not used, convert the $40 fee into RP at a much higher rate available only through account creation.
The phone option should cover the overwhelming majority of players, while the payment option is available to those who don't possess a phone number. Making smurfs is possible, but now comes at a cost.
Could this work? Why or why not?
Note: I originally posted part of this as a response to another thread, but I think it merits more discussion.