Being toxic in chat is rude and inconsiderate
But you know whats MORE inconsiderate and rude?
Its when a player queues up ranked to play like shit or troll, because he has decided the 4 other peoples time is not valuable and that he can decide for others how much value they should or shouldn't place on a given activity. Its unbelievable inconsiderate, selfish and rude. He basically is saying, "as long as I have a good time and think its funny, I don't care about other peoples time"
And guess what? Many players get chat bans for tearing into these pieces of shits. They aren't toxic players, they just don't tolerate these kinds of people that really bring the game down.
If someone trolls on purpose, like say they say they are, they buy 6
and run around dying on purpose, Riot should ban every account that person has. No warning, nothing. Just, goodbye.
That would do more for the game than banning people for saying toxic things in the chat.