So in Korea they made it so that you have to register for adult accounts with an ID number of some kind or like phone number, not sure on the exact details. This way all accounts lead back to the creator for punishment purposes.
You could force people to use their SSN to register, which is probably a terrible idea because of security reasons. And you don't want to make accounts paid, cuz that's obviously a huge hit to player base.
So here's my idea:
Make only Premim accounts playable into ranked play. Premium accounts are still free, but you must register with your ISP account number. This way you can transfer accounts with no problem like if you move or something, but you can't keep two Ranked Elligible accounts going unless paying for two ISP accounts. If you feel like smurfing, you do it in normals. Or if you want to do one of those Unranked to __________ races at the end of a season, you just create a new account registered with that ISP and make it your Premium account. By making it a bit of a pain to smurf in ranked you prevent people from just trolling on their smurf in ranked to blow off steam cuz they won't want to put in the effort. Each player would only be allowed to have one account in Premium status at a time. Punishment/Reports would affect all accounts equally, as would your honor tier. Your Honor rewards are not shared, just the honor tier.
TLDR:
-All accounts registered to ISP account number and your IRL name
-All accounts share same impact of reports and bans (all accounts are essentially one for purposes of behavior punishment)
-Only one account eligible to play ranked at one time, but you can switch this fairly easily by going online and switching it then doing an email verification.
-All accounts have their own Essence, Riot Points, honor rewards, and Cosmetics, but their Honor tier would be universal.
**New system punishes players for trolling on smurfs, remains 100% free to play, and rewards players even more for being honorable as they will be rewarded even on alt accounts.