riot doesnt just have a toxicity problem

it has a bullying problem

any negativity detectable by riot's systems will eventually get you punished. regardless of context so bullies simply grief in ways that are harder to get caught doing

retaliation isnt tolerated. so bullies will try to use the report system itself as a weapon against you. and provoke you into retaliating which can go on forever if they're subtle enough about it

there is nothing you can do about a troll other than report or mute them once they're in game they know this fully. and hold your games hostage with zero retribution other than the chance of getting banned. which means nothing if they're on a smurf