Like I said the chat ban is useless.
And... what's the alternative? What other solutions are there?
The game is free-to-play, so there's nothing to discourage making multiple accounts.
Its impossible to track people through their IP, making IP bans useless. The only way to realistically track unique users is through logging identification (such as state IDs or SSNs) or the use of SMS verification, both of which can be viewed as a privacy issue and can alienate users who don't have easy access to such information.
There has to be some leniency with punishments as to not alienate large amounts of the playerbase (because a surprising amount of people receive a 10-game chat restriction and then never get punished afterwards.) If the system is too strict, it's offputting to newcomers and removes the ability for the freedom of dialogue in things like premades and the use of swears.
An automated system can't consistently or efficiently crack down on intentional feeding, AFKing, or trolling, so they have to be manually reviewed. Manual reviews take time and are subject to error or bias.
What else can Riot do? I honestly don't see any alternatives.
At what point does the community take responsibility for their actions?