Why am I being forced to play with people I have reported and blocked?

I was just in a ranked game with three people who are queued together. They were feeding, laughing about it, and just being incredibly toxic in-game. I immediately blocked them and reported them before getting into my next match. Then, after queuing up, they land on my team in the next champ select. In this situation, I am forced to leave queue and get punished to avoid playing with people I have already told Riot I do not wish to play with. Why is this happening? LOL is widely considered the worst community in gaming, so here's to hoping Riot takes a small step to improve our experience.