I believe this is part of the move to the uniform 7 day payout period. What you're talking about was how post payouts were extended. With 7 day payouts all posts have 7 days during which they can earn rewards. Which created the issue of people knowing exactly when their last chance would be to exaggerate their rewards without risking a counter vote. If there was no lockout period everyone would wait till the last second of their payout period and upvote themselves, or create bots to do the same, and the community would not be able to counter that decision. The lockout prevents that pretty inevitable scenario from having to play out.