I don't see how people spamming "Good post :)" on every bad post on the platform will create any long lasting value.
only the pool for comments under low-value post will be greater. Someone still would need to vote for that.
If someone would leave a great comment under average post and only X would vote for that, this comment should receive more reward comparing to situation when exactly the same comment would be posted under post which already has great value and also would be voted be the same X.
That would actually cause that "great post" comments (which were posted only to be rewarded) would almost never appear under great-value post.. because those comment would need to receive tons of votes to get meaningful payout from smaller pot.