If a centralized token is added, then this central authority has incentives in increasing the amount of tokens for staking because ultimately the amount collected will be going into their pockets. Checkout what upwork is doing with paid tokens/connects.

Additionally this can also favor certain thoughts/groups by the central authority. ( The jury itself will be selected/hired by the central authority. ). Large number of posts get removed from social networks, because they pertain to certain thought or are against some govt.