being bad and plays like piece of trash won't get punished at all
Yeah, not being "good" isn't a punishable offense. Not here, and no other game that I know of. And that's how it should be.
Harassing someone for not being good enough for you isn't going to magically make them better. More likely it'll tilt them and/or make them not want to cooperate with you at all. I'm going to quote Ghostcrawler here;
what do you think of Leagues "harassment" policy? A player on your team making a "stupid" mistake at 40 min, causing you to lose game, wasting 40 min for 4 other people. why does riot take the side of the person who lost the game for his team? what are your thoughts on the language used in Games?
Everyone makes mistakes. Faker makes mistakes. Sometimes.
I don't feel that justifies giving someone a lot of shit. If they are truly being careless or taking dumb risks, I would point that out in the interest of helping them to get better, but err on the side of being conservative here. In my experience, players tend to think innocent mistakes are not innocent, or think that accidents could have trivially been prevented. I think we all expect more forgiveness as players than we are willing to give out to others.
There is no excuse to harass anyone in League, period. Nothing someone can do in a game can justify you trying to use verbal (or spoken if they can hear you) language so harsh. There is a reason nearly every sport in the world adopts some kind of sportsmanship mentality.
The advice I frequently give players is to pretend that other player is a student in your class or a coworker at school. When you're face to face, you're unlikely to unload on someone who you are going to frequently see or work with again. Why should it be any different online? If your answer is because you'll never have to see them again, then you're kind of arguing that you're only ever respectful to people for pretty selfish reasons rather than because it's the human thing to do.