Do people think there should be a reward for referrals - have 10 referrals, get 10 rep points, have 50, get one month's free subscription, etc?
If people are making a genuine effort to attract people to TSR, the number of potential donors/subscribers will rise - do these people deserve some sort of recognition?
Not the reward your suggesting but if someone did genuinely refer someone then maybe in theory there should be some reward, but in practice as Piglet said it would be too much work and not possible to fairly monitor.