You can but, i think your waiting time would be atrocious. As of right now if you queue it lasts sometimes for a few minutes if you get a guarantee. So if everyone actually gets the option to just get one role, example mid lane, and 25 people all chose that lane, then you would be the 26th. Now if the rest of the lanes only have 10 - 15 players in queue and jungle has none then you start the wait. People who has autofill on and doesn't have a guarantee will then keep getting autofilled jungle. Now if we totally remove the autofill feature then it makes it worse. Simply because you will only be able to start games if people fill all roles. And judging the amount of people who want to play jungle, well lets just say your queue time would probably last a lifetime.