As things currently stand, you cannot pick support as your secondary because you will get support 99% of the time, regardless of your primary. To fix this problem of the system not really taking into account which is your primary and which is your secondary, just have it spend the first minute only looking for your primary role, and then it can start looking for your secondary.
I would add something like that that to this if i could http://boards.na.leagueoflegends.com/en/c/gameplay-balance/iJIogIbZ-how-to-change-fill-so-we-all-dont-become-support-mains
I don't see this making any bit of an impact.
players should simply have the ability to include or exclude whatever roles they wish, and accept the potential consequences in terms of queue times.
Whether I chose a role as primary or secondary has no apparent effect on my likelihood of obtaining the role, which can be frustrating over time
