Let's be real, the best way for Riot to act against smurfs is to sue every single website that sells account. As long as players are able to buy accounts for 5-8$ there will be a problem with smurfing.
Banning or chat restricting players has no effect when accounts are expendable and can be replaced within 5 mins for less than a skin.
Also a lot of streamers (mainly onetricks) are sponsored by boosting/smurf services, some of them even have Riot partner accounts. It is Riot's responsiblity to enforce their terms of use on these public personalities and reduce the exposure of these websites that contribute to bypass sanctions and maintain toxicity afloat.
But I doubt they will ever do this because they benefit from it in a way. People who get banned for toxicity are also those who play the most. Allowing these players to stay in the game by "paying a fee" everytime they get banned allows Riot to keep their numbers up on a game which's popularity is declining.
If Riot is able to send cease and desist letters to people developping league retro, I see no reason for Riot not to be able to do the same with boosting/smurfing services (which also contribute to the botting/scripting problems).
You also have to take into account that the soloQ MMR system is tailored to make you grind for LP and eventually get stuck (losing as much as you win or losing more than you win). This system is the main reason why smurfing is a thing, it can take you 1000 games to go from P4 to D4 on a lvl300 account but only 50 games from Unranked to D4 on a fresh-unused smurf account. As long as Riot will keep this system, smurfing will be mendatory to climb without losing sanity.
The only way out of smurfing is the following:
- rework the MMR system to calculate gain/loss according to the difference of elo between teams like SC2 (and not according to the player's number of games + win/lose streak + elo last season for placements) so people can keep playing on the same account
- improve progression rewards so people care about their progression and are more reluctant to playing on another account (because they won't have their progression on it)
- sue the boosting/account selling services so there is less market
- Riot sells smurfs themselves and links every account to the same Riot account so that when one account gets banned, all associated accounts also get banned. Thus doing "unfair competition" to illegal account-selling websites so they can't economically compete and containing toxicity to the Riot-account level (and not multiple accounts).
- Require a Riot account to play league, require a phone number to create a Riot account, require double auth when logging on a new machine
Riot has all the tools to do this but if they haven't done it in 14y I doubt it will ever happen because at this point League is just a cash cow for Riot (and there isn't much public to start playing the game in 2023 so why rework the system and bother old-addicted players to fix a dieing game?). These changes should have been done season 5-6 maximum, now is too late, the game's reputation is already done.
Even before getting to the toxicity topic, there are a lot of other points that are detrimental to league's image such as graphics, client quality, missing features, no ranked teams, lackluster event pass, no more custom game modes, no workshop, outdated champion presentation in client, no skin preview, having to rely on wiki for data, etc... So even fixing toxicity is not nearly enough to bring LoL to today's standards in terms of wide-public game.
devtrackers.gg