She flamed...
...
Why do i have to lose points in ranked cause of a toxic kid that never gets banned and trolls freely?
There's a pretty drastic difference between a flamer and a troll. Yes, they're both detrimental to the game, but trolls actively go out of their way to sabotage the game for others - flamers are just jerks who spew vitriol at others.
At the end of the day, if you're losing in Ranked, there's almost certainly more factors to it than just one individual causing your loss.
Why does she deserve a second and fourth chance and one game isnt enough?
Because Riot believes that players will generally reform swiftly after the first punishment - and they typically do. Yes, that Poppy may have been toxic, but who knows why? They could've had an off-streak of games and, for whatever reason, kept playing against their better judgement. Maybe they made the mistake of playing while not in the best frame of mind?
I can't imagine straight-up permabanning players for the first offense universally, save maybe for Gameplay-related offenses and hate speech, but regardless, as long as Riot believes in player reform, they're not going to outright ban anyone and everyone from the game for lighter offenses.
Do we have to lose more points cause of them?
You lose LP because you lose matches. You lose matches because of a number of factors, and one of those factors, believe it or not, is you. Very rarely will you have matches where there's nothing you could've done to change the outcome, and it's even rarer that all of the blame for a loss could legitimately be saddled on one person.
Stop focusing on what others are doing, and focus on yourself and what you can do.