My ranked placements

So can someone explain to me how i can win 7 out of my 10 placements, in which i carried every game, and get placed in bronze 5 with 0 lp. Like wtf, i could have lost all my games and be in the same place. It makes no sense that i carry teams and the make me play at the worst level. It is like all the placement matches mean absolutely nothing and you rank is just drawn from a hat. Before anyone says anything about of you must be bad or bronze are meant to be there. I am not super at the game but i do believe that winning games should make you go up, not down.