The NA IFS, for whatever reason, takes "toxic" chat logs very seriously. Also, a lot of people who play league get offended by chat very easily and there is a culture of "I refuse to press the mute button" because people rather get all riled up and then cry to the report system.
My advise is to let the anger out audibly under your breath. I say the meanest things about my teammates but have been refraining from typing them. Crazy how much its made my win rate go up. I've literally lost countless games from poking fun at my teammates mistakes only to have them soft int and play worse on purpose to make us lose.
So yea, I would say to use the chat as minimally as possible. I don't even know why there is a chat box in the first place. Everything can be communicated via pings. The "strategic benefit" of chat has surely been outweighed by people getting in silly arguments and throwing games