Lets say you press the "FIND GAME" button, after 30 seconds, you get matched up for a game. You call your lane or you get your role (if ranked), the game starts. What do you not know is that you actually are in one of those games where the enemies are stronger and have a better mindset.
As you're playing mid, you see that the toplaner is 2/8/0, the game goes on, and you start flaming him (calling him the worst names and stuff) and calling him an INTER and a TROLL for picking Vayne toplane.
The game keeps on going and you keep flaming and flaming, spamming on all chat "report vayne inting 9x ty" , the enemy replies "shut up, flamer" and as usual you reply "STFU noob" and you now keep on flaming your team mates AND the enemies.
Your attention to the game is nullified, you don't think straight, your score is 4/12/5 and your toplaner is 5/10/15.
You lose and at the post-game screen you report Vayne for trolling and inting, meanwhile everyone else are reporting you for verbal abuse (the count doesn't matter anyway)
After a couple of minutes later you're getting notified that you have been banned permanently for toxicity.
You come on boards and cry about world being unjust, and Riot is not banning inters and trolls.
The community will reply: _**Guess what "Frank" what you actually had in that game wasn't a guy intentionally feeding nor trolling, in that game you only had a flamer ruining the game experience for someone that did his best to win the game **_.
And the sad part is that, in your mind, you keep thinking that poor Vayne did something wrong and should be punished and you should be praised as a hero that "defended" himself against flamers and trolls.
And this my friends, is the standard scenario for someone getting banned for verbal abuse.