So, autofill is a hell of a mess. Some peoples will argue that it's less often that they don't play a role they're not autofilled in than before. Thing is, it's nowadays more likely for players not to talk about what they want to play anymore. "Pref X or Y" is gone.
It's because you have to play roles you don't want at pecular times that you're less likely not to play it and switch with someone else on occasions. Having your own role become both a selfish behavior and a frustration in case you play ADC (because of filling supports).
It was less frustrating when I was last-pick support than forced to. One made it look like a team effort, the other is blatantly a thing that is pushed to my face.
It's also a TERRIBLE experience for newcomers.