Yours is not a solution either.
I work as an (unarmed) security officer. We have gates that lock down/lock out intruders. If there's an issue with us not letting people through, and we cannot de-escalate the situation, we are instructed to notify law enforcement. That's all proper procedure, and that's all fine.
However...if the intruder is armed, is that going to stop them from firing? No. They're still gonna fire the shots. They'll still be locked out, they might miss...but the shots are still fired and the damage is still done.
I can mute every person, every game whether the moment there's an issue or before there can ever be one...that's the equivalent of stopping them at the gates. But there's still an issue. There's still someone screaming in all chat and not playing the game, and their lack of presence from doing so is still the equivalent of damage done.
This is why I say - these people cannot and should not be let off the hook just because there are preventable measures to stop you from hearing them. If you are throwing the game because you'd rather spew toxicity and hatred than play your fucking champion, you are still a problem, and THAT problem is not solved by muting.
It's still my opinion they need to focus more on finding better ways to detect and dole out punishments for people intentionally trolling games or just inting when they don't feel like playing anymore...but vehemently toxic people are consequently failing their teams in similar fashion by playing all-chat instead of the game - regardless of if you can hear them or not.