I don't think the issue is rewards or the like. I think some tend to avoid healer/tank positions simply due to failing (or being lazy but I'm not one to judge on laziness, it happens to the best of us). So how would we address this? We know toxic people do exist, and plenty of friends have stated thats precisely why they never want to tank/heal for randoms.

Also to the OP, that is a terrible idea....and it doesn't solve the issue.