I don't know what to do to get more people to be the support, but this is definitely not it. Incentivizing people with meta-rewards would attract all the wrong people to the role. The people who think Support Yasuo is a thing in an already overspecialized team, who expect to get as many pentakills as they did mid lane. Then the people who actually do the role and know how it works? They're less likely to get the role.
I think this is indicative of a massively growing problem. You have to go through the shit to be a support these days with how toxic everyone is to the role, how overspecialized everyone insists on being, and how many roles the support ends up fulfilling. This is NOT sustainable in any way shape or form. And going "oh it's just a bronze/silver/gold/platinum issue. Once you get to Diamond, people actually play smart" is not just the dumbest argument in the history of the League, it's counterproductive. It shuns away new players (already a tremendous issue in League in general) from the support role, a role that bears tremendous responsibility. It's like being in the army, and the cadet is expected to captain the supercarrier.