Ranked 5 Mismatched Players

Hello summoners/hopefully a Riot person. My ranked 5 team has struggled our way to Bronze 1, but we have still enjoyed the challenge and pursuit of reaching higher tiers. However, we’ve encountered an increasingly frequent and frustrating problem recently. Many of the teams we are matched against have one or two platinum tier solo queue players, and sometimes include a diamond tier solo queue player. The strategy of these teams is simply to get that player fed, and despite our best efforts this often succeeds as the player is far superior to us in many aspects of the game. His/her teammates are not, however, yet they reap the benefits of a far superior team based on the play of one far superior individual.

This leads me to ask why, like in solo queue, are ranked teams not prevented from playing with members multiple tiers above them? This seems like (and quite frankly, commonly is) an easily abused aspect of the game and has taken much of the enjoyment out of the game for our team. This issue seems to not simply be confirmation bias, as 5 out of our last 9 ranked opponents have included a platinum or diamond tier player.