Autofill ruins the game experience, here's an idea to improve it
The very idea of forcing players to play a role that they don't master in order to find games faster, is against the very concept of competitive playing.
In ranked at least, there should be no autofill, and we should tag 3 roles instead of 2. For instance, if I'm a jungle / supp main, and I'm able to play mid correctly. I would tag Jungle / Supp / Mid, and I would never have to play adc or top against some Draven main or some OTP Riven.
I think it's reasonable to ask players to be able to play at least 3 roles correctly. With the current autofill system, you have to be able to play all roles, and especially support (many people troll instead of playing support, because they got autofilled)
My idea would make the waiting period a bit longer, but it would make the game experience so much better. Less feeders, less flamers, less trolls... for everyone.