Here is why we need to be understanding and know why there is a reason troll exists
The reason Riot does not ban troll is because most people who play this game are essentially trolls. I am merely a Gold2 and yet I am already top 10 percent of all the players. You can only imagine how many trolls or people who do not care at all are playing this game. I can also assume that those 90% people (maybe 50% cuz there must be people who actually try to climb) contribute more money to purchase RP and stuff than the rest 10%. So how can RIOT actually ban those people? If it does ban them, who is going to pay for its employees' salaries? In addition, they are not only trolls; they also unite together so that even when you report them, they would ignore this sort of actions which we consider troll. So why even bother report after all?
Same reason applies why it is worse to flame or to curse a troll than actually playing like a troll. Because there are always going to be more trolls, you would never be able to make a justification for yourselves. Almost instantly will they defend each other. Riot will not want to have flamers in their game, espcially those who play well and flame, because they might chase away its potential source of income. That is why flamers get punished more easily than trolls. That is also why there will be more people down voting this post than up voting. This is also the reason why my post will be gone within a day. Because they unite together! And controll the speech so that those words against them will all be reported and wiped away!
Also, I guess we also need to be a bit understanding. After all, many people troll to have fun, the fun they can hardly have in real life. Do you think it is humane to take away their last chance to have fun? I didn't understand why trolls never die out as well. But now that I do, I also understand why thieves dont get their hands cut off, etc. We need them as well to make us look more moral after all. Even mosquito has its value.