Here is the proclamation by riot. "If you're getting flamed mute the person."
Let's work within the bounds of that logic ok? In theory the chat box would be used to help dictate what you do in the game, however in the actual game almost every action if not every single action is dictated by pings. So what is the point of the chat box in reality? The point of it is to flame people, which is exactly what ends up happening 99.9% of the time after the game gets going.
Pro's NEVER use the chat box, they use voice chat or pings, so why the fuck do you still have a chat box? I mean seriously, it serves no logical purpose in the game other then to get people banned, for being angry and expressing that anger in chat. So just get rid of the fucking chat box, have one before and after the game if you MUST have one, but there's absolutely no reason at all to have one in the actual game. Pings are perfectly ok for indicating exactly what you need to do without a chat box.