And that's fine, you can disagree with me.
But the point in the matter, players do care. That's why they report players and they get punished for it. The system was made for the players who pressed "Play" for the game and not the whole wall of text that really leads nothing but to a semi-afk player who's spending more time to confront who's either hurting their feelings, defending another player or simply just trying to get a reaction. The main point of my post is that it is simply against the rules to retaliate. I'm sorry that you had to experience this first hand, but for any player who truly cares about their account or the game in general, they'd take the time to research it and understand it. That is why I am a player of 8 years and I've had my rough ends in this game, but I learned and I've experienced it all.
Which brings me to my conclusion. There's no reason why you couldn't research and learn what's appropriate for ingame. As for nothing is being done for toxic players, you couldn't be more wrong. Out of all the games, I've played this company is the most evolved company in MobA history. I've been a DotA player since 2002 when it was on Frozen Thrones, we created a system on Frozen Thrones to ban players. Riot's system is incredible and taking more action I've ever seen from any game in general. But as for your ban, there's not much to say except you should have learned the rules. If you cared so much about improving your gaming experience, skills, and overall attitude, you would have learned and known how to avoid the ban. But you do get another chance, I'd take this time and learn it if I was you. Then maybe, your perceptive will be quite different and you'll know that a premade team is hardly a problem when you have them on mute. Then you'll be doing exactly what you intended to do when you (like all of us) pressed "Play" and try to win the game or move forward in trying.
Continue doing so and you'll be fine.