Why do you get auto-fill protection when you play support?
I encounter more players who are auto-filled to top or jungle than I do support. When I queue as top/jungle secondary, I tend to get it probably 50% of the time, but when I run support secondary, I get it maybe 1/10 games.
I'm glad that I'm not encountering support mains auto-filled into other roles, but at the same time, I feel like Riot is implicitly acknowledging something with this. If you don't expect a support main to be able to fill into any other role, why do you expect it of other roles' mains?