My perspective after playing since day one
So i've had 4 accounts banned now. I know what you're thinking, this is a troll who is going to flame me etc etc. No, not really, i've had my bad games back when i was younger that I would rage and all that. I'm beyond those days. I just started my 4th account after being banned, i played teemo support for the majority of the leveling process. Now this new account is banned for 14 days.
During the days prior to the ban on the new account, I did an experiment. I did not say a single offensive phrase or word to anybody, I just merely talked as and commented to players, trying to get them to talk to me and have a good time. What I received was verbal abuse of the highest degree, what I would have said to people back in the day. In the end, I believe I was reported mainly because I was merely typing in this game, there was no possible way I was banned for verbal abuse because there was none.
This game is maybe the most thin skinned thing in the world. I was banned purely for typing and trying to make people at least laugh on the other team.
My plea is this: You must be able to take a slightly negative comment, you must be able to endure playful banter, you can not have a 100% safe space where nobody is ever allowed to speak their mind. I'm really not sure why chat hasn't been removed from this game because it literally serves no purpose and never has except to cause people who can't take a slightly negative comment frustration. Riot and the player base needs to grow a millimeter of skin and be able to at least speak to other players without reporting them or remove chat out right from the game.
If riot was serious about resolving this issue chat would've been removed a long time ago, anybody who actually communicates uses 3rd party programs.
TL;DR: Riot keeps chat in the game to cause people to lose their account so they have to spend money to get back to where they were...