S6 role select WAS the solution
Normals and low tier had low queue times. Autofill was only enabled when queue times were over 10 minutes, which only really affected top tiers. People waited 2-5 minutes if their role wasn't support, which is not very long, a single YTP or music video. Everyone was happy. The problem was dynamic queue, which uhm... the solution for that was putting soloQ back in place of dynamic queue.
S6 role selection already solved ALL major issues with Queues in LoL. A: People got their role B: Games were less toxic and dodges were rare C: Queue times were pretty average for any videogame
Only people who experience LONG queue times were people that queued mid/top. And even THEN it was 3-7 minutes on average. Which was fine, the reward for going support/jungle or jungle/adc was low queue times.
Autofill was never necessary, ever. S6 Role Selection was the ideal design, the problem was dynamic queue, which was not role selection. It was how people were matched up and ranked and could play with/against premades of 2-5 people.
Solution? Go back to S6 role select but with SoloQ. People who want to play with friend(s) can queue for normals, OR if queue times are not too long Flex Queue. No autofill. No DuoQ. Just SoloQ and Normal Draft(I won't get into the blind pick issue). IF Queue times can be short enough Flex Queue can be kept. Flex is a joke anyway however.

