Why do we get match made with people we report?

We just had a game where our jungle inted and flamed essentially all game. After all 4 people reported him, he winds up back in a game with me. And what's he do? Bans my main right off the bat. How is this behavior tolerated? And why do the people making the reports pay the price for a system that takes way too long to stop this behavior? If he is reported then obviously the person doing it does not enjoy playing with him. Why put them in a game together again?
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