It would be a good idea to be honest.But then again just imagine the abuse.
It is no secret that there are people who are scams and possess 100 or so accounts.This would give them exactly what they needed to get these rewards.

Even if we are more or less about 1mill users there are accounts that have 25K + followers.
Well i guess that under specific circumstances it could work...(activity of the account, comments , active followers...)
Nice idea though