So toxic

Why are some people so toxic on here? I just had a bad match as in jg and some punk as as adc was carrying the team (which isn't that hard because is broken af) because that's what adc is supposed to do and the entire time he was saying everyone else sucked and made it sound like he was the only reason we were winning. After the game he repeatedly called me a loser and ragged on the team some more eventually that he hopes I die alone. What is Riot doing to try to remove this sort of behavior from LoL? Are they doing anything? This sort of behavior should not be allowed.