In all seriousness, I am somewhat puzzled as to what the OP truly expects in an answer to his query.
By way of example, if someone yells at you on the street, you can choose to walk away, to respond back or to retaliate (with disproportionate violence if you so desire). However, not all your responses will be justified morally and/or legally. Where your response is of a violent or otherwise illegal nature, the law will intervene, and having so breached the law, you will have no acceptable justification to your actions in that context.
The same thing happens in League of Legends and all other social groups. You can choose to voice your thoughts, to ignore the player or even to report the player in some instances. The consequence of each is clear. Saying what you feel is fine, but if you overdo it, you will land yourself on the wrong side of the Tribunal.
At the end of the day, only you can decide whether or not you will rage at your fellow players. While there are certainly techniques to help you to control your emotions, the reality is that the act of raging at other people is a conscious choice. As adults, we have to face these choices and their consequences each day - it is all on us.
We can neither condone, nor condemn you. If you believe that the other players are bad and deserving of being yelled at, then you will likely not stop; if you recognise that you lose nothing by walking away from those players, then you will likely have done it already. Do you want to be in the same former group or latter group? It is a choice that you can make without assistance.
What do you want us to do for you?