The current system still does not allow for players to readily have support as their backup position

If you put support as your secondary you will get a huge amount of the time. Potentially more then your primary position and this in part why there is a shortage of supports.

Since you are forced to pick 2 positions with this current system support secondary players all but disappeared due to there being a higher chance of getting your primary if you put a more popular position as your secondary.

So why with the existence of auto fill does a player like me who is fine with playing support about a quarter of my games have to put something like mid lane as my secondary in the first place when I am autofill immune? I would be completely fine with putting only top and being insured top when I am autofill protected and likely getting about half my games when not protected as support.

Heck evne if it ends up bieng closer to a third of my games in putting only one position I am knowingly accepting that I am likely to get put as support if my desired position is not found for me.

This might return some kind of incentive for players to have their backup position as support due to a higher likelihood of getting their desired position.

Yes, I am one of those players who readily had support as my preferred backup position in seasons 3, 4 and 5. If I did not get top I would voluntarily play support since I knew it was often open and I ended up playing just over half my games as top and just over a quarter of my games as support in season 5 and I was fine with that result.

There was incentive for me to have support as my backup in that I would usually be able to get it when top was not open to me. I did not want to play it most or every game but I was completely fine with it once every 4 games for ranked.