This is my main thought when it comes to ranked, I'm pretty decent at every role, minus adc. I'm a team player on all extents, so I thought if I could reduce the chance of someone on my team getting auto filled I could help them play better and in return I could win more games or get carried.
I actually don't have a lot of information to back this up 🤣 and I have noticed I still get games with autofilled players, but I just thought in practice this could be a good strategy, as I don't like maining one specific role.