Why RIOT is punishing player that are assaulted and not that aggress?

I only got a chat restriction, but still, my ''Teamate'' from the start have started to talk shit to only because i was playing lulu...even if we were winning they were still harassing me...So why i got punished when other play keep harassing us and don't tell me there is a mute !!!

And yes sorry for my bad english that isnt my first language.