I've been playing league for about 3 years now and recently(about a week ago) got my first real punishment in the form of a 10-game chat restriction.
I was toxic. It's not that I flamed people that were doing bad, but rather I would get in fights with other toxic people because they were flaming. It was making me tilt and it was just pretty bad behaviour overall.
Getting the chat restriction made it impossible for me to go on long rants or start fights and I had to use the small amount of messages to communicate and coordinate, and even though it was limited it was just about enough.
Even over the course of just 10 games I feel like it has genuinely improved my attitude, I care a lot less about what other people say and I don't use the chat that often anymore. I wouldn't mind if all players always had to chat by these rules as it would probably make toxicity a lot less common, but it would also have its negative effects of course.
Anyways, thanks to Riot for punishing toxic players. The system is pretty smart too because I'm now trying to be extra nice to get my rewards back. Well thought out system to reform players in my opinion, it worked for me.