Why do I have to lose because of one troll

I just had a game where my team had an easy victory but part way through when the enemy had no inhibs up and we were far ahead our jg shyv types in chat “Time to lose, I’m gonna troll because fuck you guys” and proceeded to refuse to group, throw baron and drag 3 times, and try to 1v5 for the rest of the game. We lost because we could not 4v5 their team. We were very ahead early on and pushed all of the lanes to inhibit, all we needed to do was baron and end but shyv wanted to troll and it cost us the game. Why do 4 people have to lose a game they should have won becaus one person wants to be a dick? Why can’t riot fix their system?
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