Autofill vs. Elo gain - two binary oppositions

Autofill is basically synonymious with elo loss. Why?

1. Autofilled players in the most impactful roles is an obvious disadvantage.
2. Who gets the most autofilled players?
3. Which autofilled player is worse on their chosen champion?
4. In low elo a lot of people can only play 1-2 roles, perhaps onetricks.
5. Getting autofilled affects your mental stability knowing you can't do your best.