The reward pool is the same no matter what. So paying for previous posts would not matter since its just people choosing to use use their SP on "older posts". The problem is that if older posts would be able to get rewards then it would be putting a lot of extra information and transactions that the blockchain have to deal with.

It's a problem looked into by a lot and many wants to solve but none have come up with a solution to this.

But I agree, the man who figures out this problem and allows older posts to get payout should be awarded with a million steem lol.

Hopefully it will become possible in the future:)
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