Why am I getting put in a game, with the person I just reported?

Played a game where I failed a gank top, and gave a kill to the enemy top. Anyone can do it, Top lane didn't follow despite ping and that gnar 3 hit with ignite combo bopped me. But then the nasus says no you lose now. Feeds a kill immediately, then tps top to feed another kill. To then follow me around jungle and steal my farm. I mean I didn't do well and was a bit tilted, but who wouldn't be? I then got back into queue after a 20 min ff and got him in my next lobby, the same exact three people from the last game. My question is why am I being put in a game with a person I reported? Like It just ruins the night and makes anyone not want to play league, because now I have to dodge and lose some lp just for this prick.