Assign a "Shotcaller"
Thought: Like you select your role, you should also be able to say if you want to shot call or not. When lobby is created, one of the people who volunteer to shot call are assigned the "shotcaller" role. They get a icon above their head in-game and next to their name in chat so the team remembers who the shotcaller is. Pings could be different for the shotcaller as well.
Hopefully will help unify teams in solo queue and eliminate some internal fighting over what call to follow, creating less toxic and more competitive games.
"5 guys doing something bad together is better than 5 guys all doing good things, but separate" - Reginald