How to ban toxic players forever

there is an easy way to ban toxic players forever

how about asking for a phone number when creating a new account ? and u cant activate the account with out a real phone number ?

so when u ban a toxic player .. he cant make a new account .. even if he did use his friends phone number he cant make more then 4 accounts for sure

dont tell me riot cant do it -_-

Edit : from the down votes i think something wrong with the idea .. can you guys tell me why is it bad

cuz i used play a game with this system and it wasnt bad :|