People want to experience ranked with their friends. Work together to obtain larger goals (gold in most cases)
I hate to say this but: Get good?
Seriously I don't play ranked a lot but when I was in bronze IV I only did solo que all the way to silver. This was all as a support by the way and I got from bronze IV to silver in just 4 days it was nothing to me and I didn't have some ADC qued up with me.
I've seen duo ques get beaten badly by single ques, I've seen it the opposite way around.
And I've gone against duo ques hundreds of times by now and I just don't see a fukin difference. A LOT OF PEOPLE do not want to play normals all they want to do is play ranked and they want to play it with their friends. So rito says "fine want to play ranked with your friends? Alright to keep it fair for the other team we're only letting you play with ONE friend."
And this is totallyyyy fine. Again, I hate to say this: If you're losing to a duo que, you're just BAD. It's not because they have communication, it's not because magic duo que powers. It's because you are BAD and you deserve to lose.
I duo que in ranked, I duo que in normals. And there is no difference between how bot lane plays out. (As I'm a support main and all the people I duo with are usually ADC mains I found along the way) If me as a duo que wins bot lane it's because we played better.
I'll give you an example:
I used to duo que a lot with someone named "Mist3r Vain" he isn't really online anymore but we played a LOT and I do mean LOT. We duo-qued in ranked I think when I was silver V or something and we went between normals and ranked. We never talked on skype, we only communicated through in game chat and pings. We went from Silver V to like Silver III then he stopped playing and we stopped duo-queing. So it was probably around 50-70 games together in normals and ranked.
Did queing with him make it more likely I would win? Yes. But that's not because we had communication (even if we did use skype it would be no different) it was because we both knew we were good. We qued with eachother because both of us believed the other person was good at the game and we didn't want to deal with some shithead who didn't know anything about the game. The only disadvantage you are at when someone has a duo que bottom lane against you is that they are probably both good at the game. You might be good at the game, but your random que ADC might be garbage. IT's a 50-50 chance you'll either get a good ADC partner or a bad ADC partner. Either way, you can still beat that duo que lane you just have to be BETTER than them.
And that's the whole point of ranked you have to be BETTER than your opponent to win. Imagine that you have to have SKILL.
For anyone who wants to watch noobs play a duo que lane here you go a really cheesy montage of Mist3r Vain and me: (Which he made without me even knowing actually)
https://www.youtube.com/watch?v=O5oDneJ066E&list=LLDs_xh7gL6Qw--SB3-eJezw&index=4