Before all of you 12 year olds out there type "because they are toxic", read what I have to say:
...D'you really have to start the post with an insult based on age-assumption?
Really?
Alright, this may sound like I'm complaining, but I really want to know why Riot permabans toxic users. I mean, to prevent toxicity, why not just permanently restrict the player from using chat? If rudeness in chat is the issue, wouldn't taking away chat privileges solve the problem? I really don't see the need to take this much of a drastic step.
Cheap insult at the outset aside, you don't sound like you're complaining. In fact, even with the insult, it doesn't sound like complaining.
But, as others have told you, Riot has already tested what was effectively indefinite chat restrictions. The majority of players under longer-duration chat restrictions would resort to trolling, and so, Riot decided that giving CR after CR after CR wouldn't cut it.
Which, suspensions (14-day and permanent) are meant to reinforce the warning against negative behavior while simultaneously trying to cut players off from doing the same thing over and over again - or just doing worse. If the majority of players who couldn't chat just trolled or fed - why not cut them off at the head and give them equitable punishments ahead of time?
Though, that may sound like a really weird, impractical, and downright unfair ideology - why punish people on a level above their actual offense? The issue lies in the fact that - when it's necessary to punish someone for the umpteenth time, it's equally necessary for that umpteenth punishment to be harder than the last.
And if a player gets to the suspensions - they've proven twice that they don't care about the rules. They've proven twice that they're unwilling to heed warnings. The suspensions are there to give them a hard, bold-face stop when they keep ignoring the rules. And if they ignore the rules a third time...Can we really expect the fourth time to be the charm?
I just think you should give some players a chance to get their accounts back, because not all people get 20 accounts banned and take it as a joke, some people care about the time put into their account.
As others have also mentioned, the Level 20 Challenge was also a thing. Out of all the players Riot hand-picked for the challenge, who were considered most likely to succeed, 95% failed. That is a colossal failure rate, and after seeing it, Riot chose to never offer such a challenge again.
If you got an account banned, it's gone. You've proven - on that account - that you were unwilling to abide by the rules, and as such, you're no longer allowed to play on it again.
Would that the Level 20 Challenge had a higher success rate by far- but, in such a world, I'd imagine people would be well-behaved enough to not get punished in the first place, let alone banned.