As lots of people commented on this thread, we did it because of toxicity/gameplay concerns.
People would dodge to manipulate queue, trying to have the highest ranked teammates possible. This, when lots of players try to manipulate queue in this way, can severely effect match making.
People would target players based on their rank. If you were top rank on your team, but bottom of the scoreboard, you would be more likely to get flamed.
Players would avoid bombsites, or areas, based on the ranks of players. If you were the highest rank, and sitting on B site, teams would avoid B site. Or teams would focus on sites guarded by lower ranked players.
It also put a lot of emphasis on ranks, without much benefit to the players. Our goal is to make sure you are playing ranked to win, not to focus on the ranks of your opponents/teammates. Because you can control your performance, that's what should be your focus.