Flag computer so banned people can't create other accounts.
RIOT needs to implement some kind of hardware detection method, or some kind of software flag, like an entry in the registry, or a file, to stop people from creating new accounts on that computer. This would stop the endless cycle of toxic smurf accounts.
Granted, some public computers would effectively be permabanned for good players, but I suspect that would be a rare occurrence compared to most people owning their own computer. Exceptions for public computers could be done.