Let me cut straight to the point: Autofill is pointless and is hurting more than it's doing good (from my experience)
I get that autofill is here to cut down queuetime, but that's not how it works.
First, if someone on your team gets autofilled, there is roughly a 50/50 chance that they'll leave. If that happens, you either get a new game instantly or you will have to wait another 3 min again, mainly because the player that left was the support.
If they stay, you have someone who on a role they don't know how to play. I play with my friend who mains adc, and that is NOT a fun time for him at all, hurting the gameplay for 2 people in the process. Not only that, the person HAS to be carried to win the game unless they have some experience being a support, but still not a good time.
This is not that bad in normals, but in ranked, oh boy, that is so terrible.
Now if I get support, I'm leaving. I'll take the 5, 10, 20, 2 days penalty, I don't give a damn. I can't play support and I am not at a high enough ELO to find it necessary yet. So yeah, 5-10 min for me.
Overall, cutting down time is not worth any of this and you aren't cutting it down at all. I didn't have any problem with queuetime before you implemented autofill. I don't get why you ever thought that. Who told you this? What are your data on this? Please elaborate. (I know people asked for lower queuetime, but in ranked it's NOT worth it)
OR, you could just release your own data, so we could see it from your perspective. I mean, you have the data to back up your decisions, right? So I don't see why this should be a problem?
Not mad, I mean yes I am, but Riot please fix this.
Edit: To all the support mains I triggered, getting an autofill adc sucks probably even more, I know, but it's not as frequent as getting autofilled support.
Edit-2: Sun shines one again! https://gyazo.com/0d5e76ed531a458675729c57bd0176dc