You know what I've noticed a lot more this season? Auto-fill rant.
People that play support are truly people that love the role, people that have the main instinct to play a role that's more protective than offensive. People that play mid lane aren't always lovers of the role or lane, they just might need to carry and they can from mid so they might queue up for it. Same with ADC. People who play top are people that want to have a high impact in the game from TP's and roams, (sadly not as much in the gangbang bot meta).
So I guess my main point is that no matter how much you tell someone to play support or learn the role, they are never going to be anywhere close to as good as the support main on the other team. That is just not their playstyle. For instance I can go mid and I genuinely love playing mid, I love how hard of an impact you can have by roaming top, bot and through their jungle. I can play top and genuinely love it because I like being the unexpected surprise that ganks bot lane with a TP. I cannot say the same about support, ADC or Jungle though. I don't like being babied so to say. All these roles have some form of babying. Support has to literally stay with the ADC for a good portion of the game/teamfights, ADC vise versa but still kinda babying, and Jungle has to most of the time peel for the ADC with the Support. Middle and Tops job depending on the champion chosen is to get to the back line and try to blow someone up (mid) or displace them and zone them from the fight (top).
I don't know I just thought I would analyze why I hate playing the other 3 roles so much. I will however play ADC time to time to get rid of the feeding bot lanes that I may get in some of my games where the ADC just doesn't learn from their mistakes and keeps repeating them over and over again, but it doesn't mean I like playing it.
For instance I am maining Irelia top this season, but so far I'm doing O.K. I would say, there are some games where no matter what I try I just can't win but that doesn't necessarily make me mad. I'm sure I coulda tried something else to make us win but the chance of me thinking of that other thing is pretty slim in the moment. But I would like to see something done about auto-filled bot lanes that just go out of control feeding when I'm trying my absolute hardest top to do everything as humanly possible to win the game, just to be deceived by the enemy's 9/1 twitch, or 8/2 Vi just roflstomping the whole team. I am noticing a huge difference in snowball this season from the end of last season, primarily because last season you were GUARANTEED one of your two roles that you actually knew how to play. Now you can get a role that you maybe play once out of every 100 games, that puts you at a direct disadvantage if you vs a main on the other team.
TL;DR: No one queues for support just because they want to win the game. They queue for it because they love it. When you get auto-filled vs a support main your chances of winning are reduced and I would say reduced by a pretty good amount, unless every other person playing their role is on their main champion, half the time not the case.