Its not that people like autofill. It's that it's a necessary evil because there are not an equal number of people playing each role.
If there are 100 people queued up to play and only 10 supports, then 50 people get to play and 50 people have to wait until two of the supports finish, which can be 15-30 mins. If you are adding 100 people every minute, then the first 50 only have to wait a minute, but then you have 100 people waiting for a support. Every minute 50 games start and 100 more people have to wait.
The solution now is to sometimes make someone take the less wanted role to keep things moving along. In my youth hockey, the coach would make everyone play a game as goalie unless he had someone who wanted to play it. Same concept.
Another solution would be to let you queue up for whatever role you wanted but give you an estimated wait based on that role....like tft on day one. If you are seeing 90 minute waits to play mid and 1 minute waits on support, more people might be willing to play support and the ones that are willing to wait can do so.
What you can't do is make autofill optional because then everyone that allows autofill will get this roles a majority of the time.... a mid player with autofill on in an optional system will never get mid.