One main reason you are still in bronze or silver....
Team comp.
The average player has absolutely no idea the importance of team comp. Peel, Crowd Control, Focusing, all of these go out the window, and it's one of the major reasons players lose games. Players feel they can pick their fave champ every game and carry every single game. Some champs are designed to do that (Diana, Azir, Kat) but they need to get going and land a number of kills.
It would be helpful if Riot had a suggestion option in team select. Perhaps this would only be available at levels 1 - 30, and be disabled in ranked play. It will at least give new players the information they need IN game on what champ counters what. and also what is needed to fully make a team flush.