I should not be matched with players on my block list - against them fine, but not on my team. I don't care if I have to wait an additional 10 minutes for a game. I put them on the block list because I hate playing on a team with them. It has happened several times in the last few days and if it keeps happening I will simply afk and they can play a game they are 95% certain to lose while I go play a game other than LoL.
If you simply wait a bit before requeueing instead of immediately hitting that Queue button again, you have about a zero % chance to play with the same person. If you both immediately hit it after your match, you have a much higher chance of it.
The likely reason that they don't keep you away from players you blocked, is because of the limited pool of players in higher elo (especially at slow times of the day); you could simply block people to give yourself an advantage.
