Solution to support picking for filler role

What if RIOT was to implement a very simple piece of code that would make it so that if you selected a filler role, the probability of getting it is no higher than as if you was to pick your main role.

This would mean that people could more freely pick support as their fill role and not get it every single time. And thus would increase the amount of people that did so and the support role would be more filled and ques would not be 12 minutes long...

Ideas, suggestions, feedback?