Chatting is important, but unfortunately some people are unable to use the chat without being toxic. The overall response to your post alone proves that most people would rather see nothing on the chat at all than have to deal with someone being toxic. So while it is an important tool, it is not necessarily needed to win games. I would say it's become more of a privilege...if a player is mature enough to effectively use their chat to better their chances of winning rather than using it as an excuse to rage at their team for such meaningless occurrences, they deserve the privilege of using it. On the other hand, if a player is too immature to keep their useless comments to themselves and literally just pisses off their teammates, and throws peoples' game off they deserve to have that privilege taken away.
It really is surprising how many people really think that blaming, and yelling at your teammates for every little thing that happens is an okay thing to do. If what you are saying has absolutely no benefit to your team, keep it to yourself. At least, that's how I look at it. Maybe it's better to just say things out loud when you're playing. Go ahead and call that guy an idiot, but don't do it over chat. Don't get me wrong, I get pissed at my teammates when they continuously do stupid things in game, but pointing it out to them in an insulting way will not help us win. It generally causes them to continue their mistakes because instead of focusing on the game, they're more focused on trying to prove why they're not as bad as they're making themselves look. While I cannot say I have never rage texted in chat before; I'm human, some people really bring it out of you...I can honestly say I've never caused the rage fights. Either way I end up muting the toxic players before it really becomes a problem. Just like if you get pissed off during a game, it's probably best that after that game is over to take a little break, because going into a new game angry is just setting yourself up for disaster.